question
stringlengths 14
399
| choices
listlengths 4
4
| answer
stringclasses 4
values | context
stringlengths 732
6.9k
|
|---|---|---|---|
Food chewed evenly during mastication moisten and lubricate the lining of the mouth and this?
|
[
"esophagus",
"trachea",
"pharynx",
"larynx"
] |
C
|
Food is chewed evenly during mastication Moisten and lubricate the lining of the mouth and pharynx.
The soft palate ends at the uvula. The surface of the hard palate allows for the pressure needed in eating food, to leave the nasal passage clear. The opening between the lips is termed the oral fissure, and the opening into the throat is called the fauces.At either side of the soft palate are the palatoglossus muscles which also reach into regions of the tongue. These muscles raise the back of the tongue and also close both sides of the fauces to enable food to be swallowed. : 1208 Mucus helps in the mastication of food in its ability to soften and collect the food in the formation of the bolus.
Noisy breaths, obstructs airway if severe Drooling Difficult in eating Lisping speech Open-bite Protruding tongue, may ulcerate and undergo necrosis
Food polymers may be soluble in and/or plasticized by water. The variables include chemical structure, polymer concentration, molecular weight, degree of chain branching, the extent of ionization (for electrolytes), solution pH, ionic strength and temperature. Cross-linking of different polymers, protein and polysaccharides, either through chemical covalent bonds or cross-links through molecular entanglement or hydrogen or ionic bond cross-linking. Cooking and chewing food alters these physicochemical properties and hence absorption and movement through the stomach and along the intestine
Nonkeratinized tissue also lines the cheeks (buccal mucosa), underside of the tongue and floor of the mouth. The lips contain both non-keratinized tissue (on the inside) and keratinized tissue on the outside, demarcated by the vermillion border. The dorsum of the tongue is keratinized and features many papillae, some of which contain taste buds.Exposure of the tooth root due to loss of keratinized tissue around the neck of a tooth is referred to as gingival recession.
Volatile foodstuffs may leave malodourous residues in the mouth, which are the subject to bacterial putrefaction and VSC release. However, volatile foodstuffs may also cause halitosis via the blood borne halitosis mechanism. Medication – often medications can cause xerostomia (dry mouth) which results in increased microbial growth in the mouth.
|
Photosynthesis is initiated by what hitting plants?
|
[
"dirt",
"air",
"sunlight",
"moisture"
] |
C
|
Every split second that sunlight hits that leaf, photosynthesis is initiated, bringing energy into the ecosystem. It could be said that this is one of the most important - if not the absolutely most important - biochemical reactions. And it all starts with the leaf.
In biology, phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism occurs.
In plants, light-dependent reactions occur in the thylakoid membranes of the chloroplasts where they drive the synthesis of ATP and NADPH. The light-dependent reactions are of two forms: cyclic and non-cyclic. In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments (see diagram at right). The absorption of a photon by the antenna complex loosens an electron by a process called photoinduced charge separation.
The net-reaction of all light-dependent reactions in oxygenic photosynthesis is: 2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2 H+ + 2NADPH + 3ATPPSI and PSII are light-harvesting complexes. If a special pigment molecule in a photosynthetic reaction center absorbs a photon, an electron in this pigment attains the excited state and then is transferred to another molecule in the reaction center. This reaction, called photoinduced charge separation, is the start of the electron flow and transforms light energy into chemical forms.
In C3 plants, the first step in the light-independent reactions of photosynthesis is the fixation of CO2 by the enzyme RuBisCO to form 3-phosphoglycerate. However, RuBisCo has a dual carboxylase and oxygenase activity. Oxygenation results in part of the substrate being oxidized rather than carboxylated, resulting in loss of substrate and consumption of energy, in what is known as photorespiration. Oxygenation and carboxylation are competitive, meaning that the rate of the reactions depends on the relative concentration of oxygen and CO2.
In green plants, the carbon dioxide released during respiration gets used during photosynthesis. Oxygen is a by product generated during photosynthesis, and exits through stomata, root cell walls, and other routes. Plants can get rid of excess water by transpiration and guttation.
|
What is the process of drawing general conclusions based on many pieces of evidence?
|
[
"quantum reasoning",
"primitive reasoning",
"inductive reasoning",
"experimental reasoning"
] |
C
|
Inductive reasoning is the process of drawing general conclusions based on many pieces of evidence. This type of reasoning is the basis of the scientific method.
It is the process of drawing conclusions from premises or evidence. Types of reasoning can be divided into deductive and non-deductive reasoning. Deductive reasoning is governed by certain rules of inference, which guarantee the truth of the conclusion if the premises are true.
Concluding Observation. The first figure yields a correct inference in a simple, direct manner. The other figures yield a correct inference indirectly by the addition of hidden inferences. They can be changed into the simpler first figure by changing the position of the middle term.
The evidence used in the matrix is static and therefore it can be a snapshot in time.Especially in intelligence, both governmental and business, analysts must always be aware that the opponent(s) is intelligent and may be generating information intended to deceive. Since deception often is the result of a cognitive trap, Elsaesser and Stech use state-based hierarchical plan recognition (see abductive reasoning) to generate causal explanations of observations. The resulting hypotheses are converted to a dynamic Bayesian network and value of information analysis is employed to isolate assumptions implicit in the evaluation of paths in, or conclusions of, particular hypotheses.
The last step is to share the information especially if positive outcomes are achieved. By sharing the results of evidence-based practice process, others may benefit. Some methods to disseminate the information include presentations at conferences, rounds within one's own institution, and journal publications.
The last step is to share the information especially if positive outcomes are achieved. By sharing the results of evidence-based practice process, others may benefit. Some methods to disseminate the information include presentations at conferences, rounds within one's own institution, and journal publications.
|
Name the fibrous joint in which two parallel bones are united to each other by fibrous connective tissue.
|
[
"suture",
"cartilage",
"syndesmosis",
"gomphosis"
] |
C
|
Syndesmosis A syndesmosis (“fastened with a band”) is a type of fibrous joint in which two parallel bones are united to each other by fibrous connective tissue. The gap between the bones may be narrow, with the bones joined by ligaments, or the gap may be wide and filled in by a broad sheet of connective tissue called an interosseous membrane. In the forearm, the wide gap between the shaft portions of the radius and ulna bones are strongly united by an interosseous membrane (see Figure 9.5b). Similarly, in the leg, the shafts of the tibia and fibula are also united by an interosseous membrane. In addition, at the distal tibiofibular joint, the articulating surfaces of the bones lack cartilage and the narrow gap between the bones is anchored by fibrous connective tissue and ligaments on both the anterior and posterior aspects of the joint. Together, the interosseous membrane and these ligaments form the tibiofibular syndesmosis. The syndesmoses found in the forearm and leg serve to unite parallel bones and prevent their separation. However, a syndesmosis does not prevent all movement between the bones, and thus this type of fibrous joint is functionally classified as an amphiarthrosis. In the leg, the syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint. This provides strength and stability to the leg and ankle, which are important during weight bearing. In the forearm, the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements. Thus in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the antebrachial interosseous membrane allows for the much greater mobility of the forearm. The interosseous membranes of the leg and forearm also provide areas for muscle attachment. Damage to a syndesmotic joint, which usually results from a fracture of the bone with an accompanying tear of the interosseous membrane, will produce pain, loss of stability of the bones, and may damage the muscles attached to the interosseous membrane. If the fracture site is not properly immobilized with a cast or splint, contractile activity by these muscles can cause improper alignment of the broken bones during healing.
life cycle ligament The fibrous connective tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament. light-independent reactions See Calvin cycle.
The pelvis is the largest bony part of the skeleton and contains three joints: the pubic symphysis, and two sacroiliac joints. A highly durable network of ligaments surrounds these joints giving them tremendous strength. The pubic symphysis has a fibrocartilage joint which may contain a fluid filled cavity and is avascular; it is supported by the superior and arcuate ligaments. The sacroiliac joints are synovial, but their movement is restricted throughout life and they are progressively obliterated by adhesions. The nature of the bony pelvic ring with its three joints determines that no one joint can move independently of the other two.
The fibrocartilaginous disk is reinforced by a series of ligaments. These ligaments cling to the fibrocartilaginous disk to the point that fibers intermix with it. Two such ligaments are the superior pubic ligament and the inferior pubic ligament, which provide the most stability; the anterior and posterior ligaments are weaker.
A connective tissue disease (collagenosis) is any disease that has the connective tissues of the body as a target of pathology. Connective tissue is any type of biological tissue with an extensive extracellular matrix that supports, binds together, and protects organs. These tissues form a framework, or matrix, for the body, and are composed of two major structural protein molecules: collagen and elastin. There are many different types of collagen protein in each of the body's tissues.
In the latter condition the joint between the hamate and the fourth and fifth metacarpal bones has a separate synovial membrane. The synovial cavities of these joints are prolonged for a short distance between the bases of the metacarpal bones. There is a separate synovial membrane between the pisiform and triangular.
|
What's the best way humans can conserve water?
|
[
"use less",
"boil it",
"use more",
"salt it"
] |
A
|
The water supply can be harmed in two major ways. The water can be polluted, and it can be overused. Protecting the water supply must address both problems. We need to reduce how much pollution ends up in the water supply—keeping water from being polluted is easier and cheaper than cleaning it. We need to treat water that’s already polluted. We need to conserve water by using less.
Water footprint Water crisis Water efficiency Water conservation
The theme in 2018 explored how nature can be used to overcome the water challenges of the 21st century. This could be in the form of nature-based solutions to water-related challenges. For example, reducing floods, droughts, water pollution and protecting ecosystems could be solved using natural means, which nature uses, rather than man-made approaches. Restoring wetlands, implementing constructed wetlands, green roofs, green infrastructure, planting new forests, reconnecting rivers to floodplains, are some examples. Each of these use natural processes to rebalance the water cycle and improve human health and livelihoods.
Instead, water should be consumed at regular intervals. Other groups recommend rationing water through "water discipline.
Streams, headwaters, and streams flowing only part of the year provide many benefits upstream and downstream. They defend against floods, remove contaminants, recycle nutrients that are potentially dangerous as well as provide food and habitat for many forms of fish. Such streams also play a vital role in preserving our drinking water quality and supply, ensuring a steady flow of water to surface waters and helping to restore deep aquifers. Clean drinking water Flood and erosion protection Groundwater recharge Pollution reduction Wildlife habitat Economic importance in fishing, hunting, manufacturing and agriculture.
Water covers approximately 70% of the Earth's surface, where approximately 97.2% of it is saline, only 2.8% fresh. Potable water is available in almost all populated areas of the Earth, although it may be expensive and the supply may not always be sustainable. Sources where water may be obtained include springs, hyporheic zones and aquifers, and: Precipitation which includes rain, hail, snow, fog, etc. Surface water such as rivers, streams, glaciers Biological sources such as plants Desalinated seawater Water supply network Atmospheric water generatorsThreats for the availability of water resources include: water scarcity, water pollution, water conflict, insufficient well-depth, droughts and overpumping, and the effects of climate change.
|
Although fewer in number than chemical synapses, what type of synapses are found in all nervous systems and play important and unique roles?
|
[
"duplicating synapses",
"beginning synapses",
"dual synapses",
"electrical synapses"
] |
D
|
Electrical Synapse While electrical synapses are fewer in number than chemical synapses, they are found in all nervous systems and play important and unique roles. The mode of neurotransmission in electrical synapses is quite different from that in chemical synapses. In an electrical synapse, the presynaptic and postsynaptic membranes are very close together and are actually physically connected by channel proteins forming gap junctions. Gap junctions allow current to pass directly from one cell to the next. In addition to the ions that carry this current, other molecules, such as ATP, can diffuse through the large gap junction pores. There are key differences between chemical and electrical synapses. Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is unidirectional. Signaling in electrical synapses, in contrast, is virtually instantaneous (which is important for synapses involved in key reflexes), and some electrical synapses are bidirectional. Electrical synapses are also more reliable as they are less likely to be blocked, and they are important for synchronizing the electrical activity of a group of neurons. For example, electrical synapses in the thalamus are thought to regulate slow-wave sleep, and disruption of these synapses can cause seizures.
Once the neurotransmitter is released into the synapse, it can either bind to receptors on the post-synaptic cell, the pre-synaptic cell can re-uptake it and save it for later transmission, or it can be broken down by enzymes in the synapse specific to that certain neurotransmitter. These three different actions are major areas where drug action can affect communication between neurons.There are two types of receptors that neurotransmitters interact with on a post-synaptic neuron. The first types of receptors are ligand-gated ion channels or LGICs.
Neurotransmitters are chemicals that are released at synapses when the local membrane is depolarised and Ca2+ enters into the cell, typically when an action potential arrives at the synapse – neurotransmitters attach themselves to receptor molecules on the membrane of the synapse's target cell (or cells), and thereby alter the electrical or chemical properties of the receptor molecules. With few exceptions, each neuron in the brain releases the same chemical neurotransmitter, or combination of neurotransmitters, at all the synaptic connections it makes with other neurons; this rule is known as Dale's principle. Thus, a neuron can be characterized by the neurotransmitters that it releases. The great majority of psychoactive drugs exert their effects by altering specific neurotransmitter systems.
A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell.Neurotransmitters are released from synaptic vesicles into the synaptic cleft where they are able to interact with neurotransmitter receptors on the target cell. The neurotransmitter's effect on the target cell is determined by the receptor it binds to. Many neurotransmitters are synthesized from simple and plentiful precursors such as amino acids, which are readily available and often require a small number of biosynthetic steps for conversion.
Processes occur at microdomains – such as exocytosis of AMPA receptors is spatially regulated by the t-SNARE STX4. Specificity is also an important aspect of CAMKII signaling involving nanodomain calcium. The spatial gradient of PKA between dendritic spines and shafts is also important for the strength and regulation of synaptic plasticity. It is important to remember that the biochemical mechanisms altering synaptic plasticity occur at the level of individual synapses of a neuron. Since the biochemical mechanisms are confined to these "microdomains," the resulting synaptic plasticity affects only the specific synapse at which it took place.
Some unique neuronal types can be identified according to their location in the nervous system and distinct shape. Some examples are: Basket cells, interneurons that form a dense plexus of terminals around the soma of target cells, found in the cortex and cerebellum Betz cells, large motor neurons Lugaro cells, interneurons of the cerebellum Medium spiny neurons, most neurons in the corpus striatum Purkinje cells, huge neurons in the cerebellum, a type of Golgi I multipolar neuron Pyramidal cells, neurons with triangular soma, a type of Golgi I Rosehip cells, unique human inhibitory neurons that interconnect with Pyramidal cells Renshaw cells, neurons with both ends linked to alpha motor neurons Unipolar brush cells, interneurons with unique dendrite ending in a brush-like tuft Granule cells, a type of Golgi II neuron Anterior horn cells, motoneurons located in the spinal cord Spindle cells, interneurons that connect widely separated areas of the brain
|
What consists of a nitrogen atom bonded to some combination of carbons and hydrogens?
|
[
"an alkali",
"a metalloid",
"a chloride",
"an amine"
] |
D
|
An amine consists of a nitrogen atom bonded to some combination of carbons and hydrogens.
This is a partial list of molecules that contain 23 carbon atoms.
It consists of a cobalt(II) ion coordinated to four nitrogen atoms of a corrin ring and a fifth nitrogen atom from an imidazole group. In the resting state there is a Co−C sigma bond with the 5′ carbon atom of adenosine. This is a naturally occurring organometallic compound, which explains its function in trans-methylation reactions, such as the reaction carried out by methionine synthase.
There are also two other water molecules in the crystal structure. The water is hydrogen bonded to other water, or to nitrate groups.
Nitrogen atoms strengthen the bonding in the c-plane by bridging three icosahedra, like C atoms in the C-B-C chain. Figure 13 depicts the c-plane network revealing the alternate bridging of the boron icosahedra by N and C atoms. Decreasing the number of the B6 octahedra diminishes the role of nitrogen because the C-B-C chains start bridging the icosahedra.
Here is a sample molecule with the parent carbons numbered: For simplicity, here is an image of the same molecule, where the hydrogens in the parent chain are removed and the carbons are shown by their numbers: Now, following the above steps: The parent hydrocarbon chain has 23 carbons. It is called tricosa-. The functional groups with the highest precedence are the two ketone groups. The groups are on carbon atoms 3 and 9.
|
When do hammerhead sharks usually hunt?
|
[
"summer",
"in the day",
"at night",
"winter"
] |
C
|
Figure 29.11 Hammerhead sharks tend to school during the day and hunt prey at night. (credit: Masashi Sugawara).
The great hammerhead is a solitary, nomadic predator that tends to be given a wide berth by other reef sharks. If confronted, it may respond with an agonistic display, dropping its pectoral fins and swimming in a stiff or jerky fashion. Juveniles are preyed upon by larger sharks such as bull sharks (Carcharhinus leucas), while adults have no major predators except for killer whales, which hunt hammerheads of any age.
Adult smooth hammerheads are either solitary or form small groups. They may come together in great numbers during their annual migrations; schools of over a hundred juveniles under 1.5 m (4.9 ft) long have been observed off the eastern Cape of South Africa, and schools thousands strong have been reported off California. During hot summer weather, they can be seen swimming just below the surface with their dorsal fins exposed. Young smooth hammerheads are preyed upon by larger sharks such as the dusky shark (Carcharhinus obscurus); adults have been observed being consumed by killer whales (Orcinus orca) off New Zealand.
The great hammerhead, tending to be larger and more aggressive to its own kind than other hammerheads, occasionally engages in cannibalism, eating other hammerhead sharks, including mothers consuming their own young. In addition to the typical animal prey, bonnetheads have been found to feed on seagrass, which sometimes makes up as much as half their stomach contents. They may swallow it unintentionally, but they are able to partially digest it. At the time of discovery, this was the only known case of a potentially omnivorous species of shark (since then, whale sharks were also found to be omnivorous).
The gestation period is reported to be around 12 months. Scalloped hammerheads give live birth. Compared to other species, the scalloped hammerhead produces large litters (12–41 pups), and this is most likely due to high infant mortality. Like most sharks, parental care is not seen.
Nocturnal and bottom-dwelling, the crested bullhead shark favors rocky reefs and vegetated areas, where it hunts for sea urchins and other small organisms. It is oviparous, with females producing spiral-shaped egg capsules that are secured to seaweed or sponges with long tendrils. Sexual maturation is slow, with one female in captivity not laying eggs until almost 12 years of age. The International Union for Conservation of Nature has assessed this harmless shark as of Least Concern; it is of no economic interest and suffers minimal mortality from bycatch, recreational fishing, and shark nets.
|
What types of glands do only female mammals have?
|
[
"mammary",
"pituitary",
"thyroid",
"respiratory"
] |
A
|
Two traits are used to define the mammal class. They are fur or hair and mammary glands in females.
They are omnipresent in non-placental mammaliformes, though Megazostrodon and Erythrotherium appear to have lacked them.It has been suggested that the original function of lactation (milk production) was to keep eggs moist. Much of the argument is based on monotremes, the egg-laying mammals. In human females, mammary glands become fully developed during puberty, regardless of pregnancy.
The bony orbits around the eye never form a complete ring and the auditory bullae are smooth and rounded. Females have three to seven pairs of mammae.All canids are digitigrade, meaning they walk on their toes. The tip of the nose is always naked, as are the cushioned pads on the soles of the feet.
The adult female has a gray head, breast, and upper belly and less extensive (though equally bright) red on the lower belly. Both sexes bear the wispy hair-like auricular plumes that give the species its name, though these are rarely apparent in the field.
Most non-human mammals do not have a single uterus with no separation of horns. Marsupials and rodents have a double uterus (uterus duplex). In other animals (e.g. nematodes), the term 'didelphic' refers to a double genital tract, as opposed to monodelphic, with a single tract.
Sex organs are typically differentiated into male and female types. In humans, the male sex organs include the testes, penis, and prostate gland; the female sex organs include the ovaries, fallopian tubes, uterus, cervix, vagina, and vulva. In animals (including humans), the testis in the male and the ovary in the female are called the primary sex organs.
|
What is the unit used to measure air pressure?
|
[
"millibar",
"pounds per inch",
"newtons",
"mass"
] |
A
|
The weather map pictured below ( Figure above ) shows air pressure. The lines on the map connect places that have the same air pressure. Air pressure is measured in a unit called the millibar. Isobars are the lines that connect the points with the same air pressure. The map also shows low- and high-pressure centers and fronts. Find the cold front on the map. This cold front is likely to move toward the northeast over the next couple of days. How could you use this information to predict what the weather will be on the East Coast?.
An "air-in-line" detector. A typical detector will use an ultrasonic transmitter and receiver to detect when air is being pumped. Some pumps actually measure the volume, and may even have configurable volumes, from 0.1 to 2 ml of air.
The widely used Bourdon gauge is a mechanical device, which both measures and indicates and is probably the best known type of gauge. A vacuum gauge is used to measure pressures lower than the ambient atmospheric pressure, which is set as the zero point, in negative values (for instance, −1 bar or −760 mmHg equals total vacuum). Most gauges measure pressure relative to atmospheric pressure as the zero point, so this form of reading is simply referred to as "gauge pressure".
The basic instrument for monitoring available gas is the submersible pressure gauge, which indicates the remaining pressure in a scuba cylinder, by directly measuring pressure at a high-pressure port of the regulator first stage. Many closed circuit rebreathers use advanced electronics to monitor and regulate the composition of the breathing gas. the composition of open circuit gas is analysed before use and recorded on a label on the cylinder. The default value is air, which does not require a specific label.
Blood pressure is measured in millimetres of mercury (see torr) in most of the world, central venous pressure and lung pressures in centimeters of water are still common, as in settings for CPAP machines. Natural gas pipeline pressures are measured in inches of water, expressed as "inches W.C." Underwater divers use manometric units: the ambient pressure is measured in units of metres sea water (msw) which is defined as equal to one tenth of a bar.
Such devices are based on two types of technology: (1) time of flight or transit time; and (2) cross correlation. Both technologies involve transducers that are simply clamped on to the pipe and programmed with the pipe size and schedule and can be used to calculate flow. Such meters can be used to measure almost any dry gas including natural gas, nitrogen, compressed air, and steam. Clamp-on meters are available for measuring liquid flow as well.
|
In which stage does the chromatin condense into chromosomes?
|
[
"prophase ii",
"Metaphase I",
"Telophase II",
"Anaphase I"
] |
A
|
In prophase II, once again the nucleolus disappears and the nucleus breaks down. The chromatin condenses into chromosomes. The spindle begins to reform as the centrioles move to opposite sides of the cell.
The chromatin is then fragmented and exposed to antibodies specific to the protein of interest. These complexes are then precipitated. The DNA is then isolated and purified.
In the early stages of mitosis or meiosis (cell division), the chromatin double helix become more and more condensed. They cease to function as accessible genetic material (transcription stops) and become a compact transportable form. The loops of 30-nm chromatin fibers are thought to fold upon themselves further to form the compact metaphase chromosomes of mitotic cells. The DNA is thus condensed about 10,000 fold.The chromosome scaffold, which is made of proteins such as condensin, TOP2A and KIF4, plays an important role in holding the chromatin into compact chromosomes.
polysaccharide prometaphase The second stage of cell division in mitosis, following prophase and preceding metaphase, during which the nuclear membrane disintegrates, the chromosomes inside form kinetochores around their centromeres, microtubules emerging from the poles of the mitotic spindle reach the nuclear space and attach to the kinetochores, and motor proteins associated with the microtubules begin to push the chromosomes toward the center of the cell. prophase The first stage of cell division in both mitosis and meiosis, occurring after interphase and before prometaphase, during which the DNA of the chromosomes is condensed into chromatin, the nucleolus disintegrates, centrosomes move to opposite ends of the cell, and the mitotic spindle forms. protein A polymeric macromolecule composed of one or more long chains of amino acids linked by peptide bonds.
Chromatin bridges may form by any number of processes wherein chromosomes remain topologically entangled during mitosis. One way in which this may occur is the failure to resolve joint molecules formed during homologous recombination mediated DNA repair, a process that ensures that replicated chromosomes are intact before chromosomes are segregated during cell division. In particular, genetic studies have demonstrated that the loss of the enzymes BLM (Bloom's Syndrome Helicase) or FANCM each result in a dramatic increase in the number of chromatin bridges. This occurs because loss of these genes causes an increase in chromosome fusions, either in an end-to-end manner or through topological entrapment (e.g., catenation or unresolved DNA cross-links), have also been associated with chromatin bridge formation. When viewed under a fluorescence microscope and immunostained for cytological markers, these chromatin bridges appear to emanate from either centromeres, telomeres or DNA crosslinks (as marked by FANCD2).
The resultant tightly packed chromatin is transcriptionally inactive. The Golgi apparatus surrounds the now condensed nucleus, becoming the acrosome. Maturation then takes place under the influence of testosterone, which removes the remaining unnecessary cytoplasm and organelles.
|
What is the upper-most atmosphere known as?
|
[
"thermosphere",
"xerosphere",
"exosphere",
"ionosphere"
] |
A
|
The atmosphere is a big part of the water cycle. What do you think would happen to Earth’s water without it?.
If the atmosphere of a celestial body is very tenuous, like the atmosphere of the Moon or that of Mercury, the whole atmosphere is considered exosphere.
The middle layer of the Uranian atmosphere is the stratosphere, where temperature generally increases with altitude from 53 K (−220 °C; −364 °F) in the tropopause to between 800 and 850 K (527 and 577 °C; 980 and 1,070 °F) at the base of the thermosphere. The heating of the stratosphere is caused by absorption of solar UV and IR radiation by methane and other hydrocarbons, which form in this part of the atmosphere as a result of methane photolysis. Heat is also conducted from the hot thermosphere. The hydrocarbons occupy a relatively narrow layer at altitudes of between 100 and 300 km corresponding to a pressure range of 1000 to 10 Pa and temperatures of between 75 and 170 K (−198 and −103 °C; −325 and −154 °F).The most abundant hydrocarbons are methane, acetylene and ethane with mixing ratios of around 10−7 relative to hydrogen.
Most of the air - including ~88% of the CO2 - is located in the lower part of the atmosphere known as troposphere. The troposphere is thicker in the equator and thinner at the poles, but the global mean of its thickness is around 11 km. Inside the troposphere, the temperature drops approximately linearly at a rate of 6.5 Celsius degrees per km, from a global mean of 288 Kelvin (15 Celsius) on the ground to 220 K (-53 Celsius). At higher altitudes, up to 20 km, the temperature is approximately constant; this layer is called the tropopause.
Aeronomy is the study of the upper layers of the atmosphere, where dissociation and ionization are important. Atmospheric science has been extended to the field of planetary science and the study of the atmospheres of the planets and natural satellites of the Solar System. Experimental instruments used in atmospheric science include satellites, rocketsondes, radiosondes, weather balloons, radars, and lasers. The term aerology (from Greek ἀήρ, aēr, "air"; and -λογία, -logia) is sometimes used as an alternative term for the study of Earth's atmosphere; in other definitions, aerology is restricted to the free atmosphere, the region above the planetary boundary layer.Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann.
The mesopause, at an altitude of 80–90 km (50–56 mi), separates the mesosphere from the thermosphere—the second-outermost layer of Earth's atmosphere. On Earth, the mesopause nearly co-incides with the turbopause, below which different chemical species are well-mixed due to turbulent eddies.
|
Reproduction that doesn't involve a male gamete is also known as what?
|
[
"meiosis",
"mitosis",
"asexual reproduction",
"agamogenesis"
] |
D
|
Agamogenesis is any form of reproduction that does not involve a male gamete. These include are parthenogenesis and apomixis. Parthenogenesis is a form of asexual reproduction where growth and development of embryos occur without fertilization. Parthenogenesis occurs naturally in aphids, rotifers, nematodes and some other invertebrates, as well as in many plants and certain lizards, such as the Komodo dragon. Apomixis is asexual reproduction, without fertilization, in plants.
The mature gametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female gametes produces a diploid zygote which develops into a new sporophyte. This cycle is known as alternation of generations or alternation of phases.
Through an interplay of hormones that includes follicle stimulating hormone that stimulates folliculogenesis and oogenesis creates a mature egg cell, the female gamete. Fertilization is the event where the egg cell fuses with the male gamete, spermatozoon. After the point of fertilization, the fused product of the female and male gamete is referred to as a zygote or fertilized egg. The fusion of female and male gametes usually occurs following the act of sexual intercourse.
Anisogamy is the form of sexual reproduction that involves the union or fusion of two gametes which differ in size and/or form. The smaller gamete is considered to be male (a sperm cell), whereas the larger gamete is regarded as female (typically an egg cell, if non-motile).There are several types of anisogamy. Both gametes may be flagellated and therefore motile. Alternatively, as in flowering plants, conifers and gnetophytes, neither of the gametes are flagellated.
The egg cell, or ovum (PL: ova), is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is not capable of movement (non-motile). If the male gamete (sperm) is capable of movement, the type of sexual reproduction is also classified as oogamous. A nonmotile female gamete formed in the oogonium of some algae, fungi, oomycetes, or bryophytes is an oosphere. When fertilized the oosphere becomes the oospore.When egg and sperm fuse during fertilisation, a diploid cell (the zygote) is formed, which rapidly grows into a new organism.
In some Bryophyte and some algae species, the gametophyte stage of the life cycle, rather than being hermaphrodite, occurs as separate male or female individuals that produce male and female gametes respectively. When meiosis occurs in the sporophyte generation of the life cycle, the sex chromosomes known as U and V assort in spores that carry either the U chromosome and give rise to female gametophytes, or the V chromosome and give rise to male gametophytes.
|
What is the term for an electronic component that consists of many other electronic components?
|
[
"electrical current",
"creating circuit",
"integrated circuit",
"networks"
] |
C
|
An integrated circuit (microchip) is an electronic component that consists of many other electronic components such as transistors. Integrated circuits are used in virtually all modern electronic devices to carry out specific tasks.
An electronic kit is a package of electrical components used to build an electronic device. Generally, kits are composed of electronic components, a circuit diagram (schematic), assembly instructions, and often a printed circuit board (PCB) or another type of prototyping board. There are two types of kits. Some build a single device or system.
Online Electrotechnical Vocabulary A Glossary of Electrical Terms Electronic Terminology Electronics Glossary Glossary / Dictionary of Electronics Terms
Electrical waste contains hazardous but also valuable and scarce materials. Up to 60 elements can be found in complex electronics.
Multiple electronic components assembled in a device that is in itself used as a component Oscillator Display devices Liquid crystal display (LCD) Digital voltmeters Filter
Several terms are commonly used to characterize the general physical and chemical properties of the chemical elements. A first distinction is between metals, which readily conduct electricity, nonmetals, which do not, and a small group, (the metalloids), having intermediate properties and often behaving as semiconductors. A more refined classification is often shown in colored presentations of the periodic table. This system restricts the terms "metal" and "nonmetal" to only certain of the more broadly defined metals and nonmetals, adding additional terms for certain sets of the more broadly viewed metals and nonmetals.
|
What is another term for life science?
|
[
"biology",
"geology",
"ecology",
"meteorology"
] |
A
|
Life science is the study of life and living organisms. Life science is also called biology.
Natural history referred to what we now call life sciences and natural philosophy referred to the current physical sciences. Prior to the twentieth century, few opportunities existed for science as an occupation outside the educational system.
Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments.Biologists are able to study life at multiple levels of organization, from the molecular biology of a cell to the anatomy and physiology of plants and animals, and evolution of populations. Hence, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they use.
Botany, also called plant science (or plant sciences), plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek word βοτάνη (botanē) meaning "pasture", "herbs" "grass", or "fodder"; βοτάνη is in turn derived from βόσκειν (boskein), "to feed" or "to graze".
A sub-set of biomedical sciences is the science of clinical laboratory diagnosis. This is commonly referred to in the UK as 'biomedical science' or 'healthcare science'. There are at least 45 different specialisms within healthcare science, which are traditionally grouped into three main divisions: specialisms involving life sciences specialisms involving physiological science specialisms involving medical physics or bioengineering
Ecology (from Greek: οἶκος, "house", or "environment"; -λογία, "study of") is a branch of biology concerning interactions among organisms and their biophysical environment, which includes both biotic and abiotic components. Topics of interest include the biodiversity, distribution, biomass, and populations of organisms, as well as cooperation and competition within and between species. Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, pedogenesis, nutrient cycling, and niche construction, regulate the flux of energy and matter through an environment. These processes are sustained by organisms with specific life history traits.
|
What type of cartilage contains no collagen?
|
[
"fetal cartilage",
"lamprey cartilage",
"shark cartilage",
"joint cartilage"
] |
B
|
Collagen is exocytosed in precursor form (procollagen), which is then cleaved by procollagen proteases to allow extracellular assembly. Disorders such as Ehlers Danlos Syndrome, osteogenesis imperfecta, and epidermolysis bullosa are linked with genetic defects in collagen-encoding genes. The collagen can be divided into several families according to the types of structure they form: Fibrillar (Type I, II, III, V, XI) Facit (Type IX, XII, XIV) Short chain (Type VIII, X) Basement membrane (Type IV) Other (Type VI, VII, XIII)
Type III collagen is found as a major structural component in hollow organs such as large blood vessels, uterus and bowel. It is also found in many other tissues together with type I collagen.
The extracellular matrix of bone is laid down by osteoblasts, which secrete both collagen and ground substance. These synthesise collagen within the cell and then secrete collagen fibrils. The collagen fibers rapidly polymerise to form collagen strands. At this stage, they are not yet mineralised, and are called "osteoid".
This collagen overexpression continues and crosslinks the fiber arrangement inside the collagen matrix, making the collagen dense. This densely packed collagen, morphing into an inelastic whitish collagen scar wall, blocks off cell communication and regeneration; as a result, the new tissue generated will have a different texture and quality than the surrounding unwounded tissue. This prolonged collagen-producing process results in a fortuna scar.
Hematoxylin and eosin staining (H&E) shows that the cytoplasm of active osteoblasts is slightly basophilic due to the substantial presence of rough endoplasmic reticulum. The active osteoblast produces substantial collagen type I. About 10% of the bone matrix is collagen with the balance mineral. The osteoblast's nucleus is spherical and large.
|
In prokaryotes, what are the regions called that repressors bind to?
|
[
"elements",
"operators",
"enablers",
"consumers"
] |
B
|
For a bacteria, many aspects of gene regulation are due to the presence or absence of certain nutrients. In prokaryotes, repressors bind to regions called operators that are generally located immediately downstream from the promoter. Activators bind to the upstream portion of the promoter.
Testable outlines exist for the origin of each of the three motility systems, and avenues for further research are clear; for prokaryotes, these avenues include the study of secretion systems in free-living, nonvirulent prokaryotes. In eukaryotes, the mechanisms of both mitosis and cilial construction, including the key role of the centriole, need to be much better understood. A detailed survey of the various nonmotile appendages found in eukaryotes is also necessary. Finally, the study of the origin of all of these systems would benefit greatly from a resolution of the questions surrounding deep phylogeny, as to what are the most deeply branching organisms in each domain, and what are the interrelationships between the domains.
Proteome analyzes have shown that Nomurabacteria can be the most basal clade of cellular organisms and that the other CPR bacteria are a paraphyletic group as can be seen in the cladogram that shows the phylogenetic relationships between multiple bacterial, archaean and eukaryotes. == References ==
Low nutrient abundance may have facilitated photosymbiosis—where one organism is capable of photosynthesis and the other metabolizes the waste product—among prokaryotes (bacteria and archaea), and the emergence of eukaryotes. Bacteria, Archaea, and Eukaryota are the three domains, the highest taxonomic ranking. Eukaryotes are distinguished from prokaryotes by a nucleus and membrane-bound organelles, and almost all multicellular organisms are eukaryotes.
In molecular biology, the iron dependent repressors are a family of bacterial and archaeal transcriptional repressors. At their N-terminus they contain a dtxR-type HTH domain. This is a DNA-binding, winged helix-turn-helix (wHTH) domain of about 65 amino acids present in metalloregulators of the dtxR/mntR family. The domain is named after Corynebacterium diphtheriae dtxR, an iron-specific diphtheria toxin repressor, and Bacillus subtilis mntR, a manganese transport regulator.
Here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea. This involved the engulfment by proto-eukaryotic cells of alphaproteobacterial symbionts to form either mitochondria or hydrogenosomes, which are still found in all known Eukarya. Later on, some eukaryotes that already contained mitochondria also engulfed cyanobacterial-like organisms.
|
What instrument has a resolution many times greater than a light microscope, and can be used to see the details on the outside of a cell?
|
[
"complex microscope",
"electron microscope",
"element microscope",
"molecular microscope"
] |
B
|
Use an electron microscope. This instrument has a resolution many times greater than a light microscope, and can be used to see the details on the outside of a cell. Some electron microscopes can also be used to see the details inside a cell.
This uses a wide field of illumination. To provide magnification, a diverging beam is incident on the specimen. An out-of-focus image, which appears as a Fresnel interference pattern, is projected onto the detector. The illumination must have phase distortions in it, often provided by a diffuser that scrambles the phase of the incident wave before it reaches the specimen, otherwise the image remains constant as the specimen is moved, so there is no new ptychographical information from one position to the next. In the electron microscope, a lens can be used to map the magnified Fresnel image onto the detector.
In blue light, conventional optical microscopes have a diffraction-limited resolution of about 200 nm. By comparison, electron microscopes are limited by the de Broglie wavelength of the electron. This wavelength, for example, is equal to 0.0037 nm for electrons accelerated across a 100,000-volt potential.
Zeiss offers different types of microscopes: Optical microscopes Laser scanning microscopes (LSMs) Scanning electron microscopes (SEMs) Scanning helium ion microscopes (SHIMs)
Practically, one can achieve only aperture angles of about 140° for an objective lens, which corresponds to Ω ≈ 1.3 π {\displaystyle \Omega \approx 1.3\pi } . The microscope can be operated in three different ways: In a 4Pi microscope of type A, the coherent superposition of excitation light is used to generate the increased resolution. The emission light is either detected from one side only or in an incoherent superposition from both sides.
Whole cell and tissue analysis is possible using a microPIXE beam, this method is also referred to as nuclear microscopy.
|
The temperature at which the individual ions have enough kinetic energy to overcome the attractive forces that hold them in place is called?
|
[
"melting point",
"occurring point",
"boiling point",
"last point"
] |
A
|
The Relationship between Lattice Energies and Physical Properties The magnitude of the forces that hold an ionic substance together has a dramatic effect on many of its properties. The melting point, for example, is the temperature at which the individual ions have enough kinetic energy to overcome the attractive forces that hold them in place. At the melting point, the ions can move freely, and the substance becomes a liquid. Thus melting points vary with lattice energies for ionic substances that have similar structures. The melting points of the sodium halides (Figure 8.3 "A Plot of Melting Point versus the Identity of the Halide for the Sodium Halides"), for example, decrease smoothly from NaF to NaI, following the same trend as seen for their lattice energies (Figure 8.2 "A Plot of Lattice Energy versus the Identity of the Halide for the Lithium, Sodium, and Potassium Halides"). Similarly, the melting point of MgO is 2825°C, compared with 996°C for NaF, reflecting the higher lattice energies associated with higher charges on the ions. In fact, because of its high melting point, MgO is used as an electrical insulator in heating elements for electric stoves. Figure 8.3 A Plot of Melting Point versus the Identity of the Halide for the Sodium Halides.
Even though these motions are called "internal", the external portions of molecules still move—rather like the jiggling of a stationary water balloon. This permits the two-way exchange of kinetic energy between internal motions and translational motions with each molecular collision. Accordingly, as internal energy is removed from molecules, both their kinetic temperature (the kinetic energy of translational motion) and their internal temperature simultaneously diminish in equal proportions.
These ions are mostly Na+, Cl−, K+, Ca2+ and HCO3−. The powering force is the Na/K-ATPase on the basolateral membrane which maintains the ion concentrations inside the cells. On the luminal membrane, Na enters the cells passively; using the Na–K–Cl symporter.
An important example of this interaction is hydration of ions in water which give rise to hydration enthalpy. The polar water molecules surround themselves around ions in water and the energy released during the process is known as hydration enthalpy. The interaction has its immense importance in justifying the stability of various ions (like Cu2+) in water. An ion–induced dipole force consists of an ion and a non-polar molecule interacting. Like a dipole–induced dipole force, the charge of the ion causes distortion of the electron cloud on the non-polar molecule.
Contact between surfaces is made up of a large number of microscopic regions, in the literature called asperities or junctions of contact, where atom-to-atom contact takes place. The phenomenon of friction, and therefore of the dissipation of energy, is due precisely to the deformations that such regions undergo due to the load and relative movement. Plastic, elastic, or rupture deformations can be observed: Plastic deformations – permanent deformations of the shape of the bumps; Elastic deformations – deformations in which the energy expended in the compression phase is almost entirely recovered in the decompression phase (elastic hysteresis); Break deformations – deformations that lead to the breaking of bumps and the creation of new contact areas.The energy that is dissipated during the phenomenon is transformed into heat, thus increasing the temperature of the surfaces in contact. The increase in temperature also depends on the relative speed and the roughness of the material, it can be so high as to even lead to the fusion of the materials involved. In friction phenomena, temperature is fundamental in many areas of application. For example, a rise in temperature may result in a sharp reduction of the friction coefficient, and consequently, the effectiveness of the brakes.
(bixbyite). The heat of formation is c. 24 kilocalories (100 kJ) per mol.
|
What play several important roles in the human body?
|
[
"lipids",
"cells",
"tissues",
"organs"
] |
A
|
Lipids play several important roles in the body. Triglycerides are stored in fat cells until the body needs to break them down for chemical energy. These stored triglycerides also help insulate the body against extreme temperatures and cushion organs against physical jostling. Phospholipids and cholesterol are important constituents of the cell membrane. These compounds provide structural integrity to the cell wall, since they are not water-soluble. Other steroids are used as chemical messengers in the body, and the fat-soluble vitamins serve a variety of other functions.
The whole exhibits a discernible regulatory function as it relates to cooperation and coordination of the structure and activity of parts, and to the selection and deselection of variations. The result is a balanced correlation of organs and functions. The activities of the parts are directed to central ends: co-operation and unified action instead of the separate mechanical activities of the parts. : 125
For example, the organism may be described at any of its component levels, including the atomic, molecular, cellular, histological (tissue), organ and organ system levels. Furthermore, at every level of the hierarchy, new functions necessary for the control of life appear. These new roles are not functions that the lower level components are capable of and are thus referred to as emergent properties. Every organism is organised, though not necessarily to the same degree. An organism can not be organised at the histological (tissue) level if it is not composed of tissues in the first place.
These adaptations and changes have allowed Homo sapiens to function as they do today. As is the standard for all evolutionary adaptations, the human muscle system evolved in its efforts to increase survivability. Since muscles and the accompanying ligaments and tendons are present all throughout the body aiding in many functions, it is apparent that our behavior and decisions are based upon what we are and how we can operate.
Perspectives in Biology and Medicine. 43 (2): 161–172. doi:10.1353/pbm.2000.0002.
The main functions of the urinary system and its components are to: Regulate blood volume and composition (e.g. sodium, potassium and calcium) Regulate blood pressure. Regulate pH homeostasis of the blood. Contributes to the production of red blood cells by the kidney. Helps synthesize calcitriol (the active form of Vitamin D). Stores waste products (mainly urea and uric acid) before it and other products are removed from the body.
|
What is a measure that has both size and direction?
|
[
"length",
"vector",
"velocity",
"wave"
] |
B
|
Force is a vector, or a measure that has both size and direction. For example, Colton pushes on the ground in the opposite direction that the scooter moves, so that’s the direction of the force he is applies. He can give the scooter a strong push or a weak push. That’s the size of the force. Like other vectors, a force can be represented with an arrow. You can see some examples in the Figure below . The length of each arrow represents the strength of the force, and the way the arrow points represents the direction of the force.
There are different sizes available, varying in length, width and angle.
Sliding compasses are used to measure the "foot, forearm, and middle and little fingers". Small sliding compasses are used to measure the ear. A vertical measure is used to measure for height and a horizontal measure is used to measure for wingspan.
All ordinary measurement of length in public units, such as inches, using standard public devices, such as a ruler, implies public recognition of a Cartesian grid; that is, a surface divided into unit squares, such as one square inch, and a space divided into unit cubes, such as one cubic inch. The ancient Greek units of measurement had provided such a grid to Greek mathematicians since the Bronze Age. Prior to Apollonius, Menaechmus and Archimedes had already started locating their figures on an implied window of the common grid by referring to distances conceived to be measured from a left-hand vertical line marking a low measure and a bottom horizontal line marking a low measure, the directions being rectilinear, or perpendicular to one another. These edges of the window become, in the Cartesian coordinate system, the axes.
The concept of length or distance can be generalized, leading to the idea of metrics. For instance, the Euclidean metric measures the distance between points in the Euclidean plane, while the hyperbolic metric measures the distance in the hyperbolic plane. Other important examples of metrics include the Lorentz metric of special relativity and the semi-Riemannian metrics of general relativity.In a different direction, the concepts of length, area and volume are extended by measure theory, which studies methods of assigning a size or measure to sets, where the measures follow rules similar to those of classical area and volume.
And so on for higher dimensions. These are the measure polytopes or hypercubes. Their names are, in order of dimensionality: 0.
|
What is to blame for water’s boiling point (100°c) being higher than the boiling points of similar substances?
|
[
"electrode bonds",
"molecular shape",
"hydrogen bonds",
"helium bonds"
] |
C
|
Hydrogen bonds also explain why water’s boiling point (100°C) is higher than the boiling points of similar substances without hydrogen bonds. Because of water’s relatively high boiling point, most water exists in a liquid state on Earth. Liquid water is needed by all living organisms. Therefore, the availability of liquid water enables life to survive over much of the planet.
Non-covalent interactions have a significant effect on the boiling point of a liquid. Boiling point is defined as the temperature at which the vapor pressure of a liquid is equal to the pressure surrounding the liquid. More simply, it is the temperature at which a liquid becomes a gas. As one might expect, the stronger the non-covalent interactions present for a substance, the higher its boiling point.
The boiling and freezing points of water are affected by solutes, as well as air pressure, which is in turn affected by altitude. Water boils at lower temperatures with the lower air pressure that occurs at higher elevations. One mole of sucrose (sugar) per kilogram of water raises the boiling point of water by 0.51 °C (0.918 °F), and one mole of salt per kg raises the boiling point by 1.02 °C (1.836 °F); similarly, increasing the number of dissolved particles lowers water's freezing point.Solutes in water also affect water activity that affects many chemical reactions and the growth of microbes in food.
At this point in the maximum, considerable vapor is being formed, making it difficult for the liquid to continuously wet the surface to receive heat from the surface. This causes the heat flux to reduce after this point. At extremes, film boiling commonly known as the Leidenfrost effect is observed.
Many substances normally stored as liquids, such as CO2, propane, and other similar industrial gases have boiling temperatures far below room temperature when at atmospheric pressure. In the case of water, a BLEVE could occur if a pressurized chamber of water is heated far beyond the standard 100 °C (212 °F). That container, because the boiling water pressurizes it, must be capable of holding liquid water at very high temperatures.
As atmospheric pressure decreases with altitude, the boiling point decreases by 1 °C every 274 meters. High-altitude cooking takes longer than sea-level cooking.
|
Carbonic acid decomposes easily at room temperature into carbon dioxide and what else?
|
[
"water",
"gas",
"oxygen",
"helium"
] |
A
|
Some unstable acids decompose to produce nonmetal oxides and water. Carbonic acid decomposes easily at room temperature into carbon dioxide and water.
Carbon dioxide (CO2) is produced in tissues as a byproduct of normal metabolism. It dissolves in the solution of blood plasma and into red blood cells (RBC), where carbonic anhydrase catalyzes its hydration to carbonic acid (H2CO3). Carbonic acid then spontaneously dissociates to form bicarbonate Ions (HCO3−) and a hydrogen ion (H+). In response to the decrease in intracellular pCO2, more CO2 passively diffuses into the cell.
Carbonic anhydrase could in principle prove relevant to carbon capture. Some carbonic anhydrases can withstand temperatures up to 107 °C and extreme alkalinity (pH > 10). A pilot run with the more stable CA on a flue stream that consisted of 12–13% mol composition CO₂ had a capture rate of 63.6% over a 60-hour period with no noticeable effects in enzyme performance. CA was placed in a N-methyldiethanolamine (MDEA) solution where it served to increase the concentration difference (driving force) of CO2 between the flue stream of the power plant and liquid phase in a liquid-gas contactor.
In such a system, fossil fuels are combusted with air and CO2 is selectively removed from a gas mixture also containing N2, H2O, O2 and trace sulphur, nitrogen and metal impurities. While exact separation conditions are fuel and technology dependent, in general CO2 is present at low concentrations (4-15% v/v) in gas mixtures near atmospheric pressure and at temperatures of approximately -60 °C. Sorbents for carbon capture are regenerated using temperature, pressure or vacuum, so that CO2 can be collected for sequestration or utilization and the sorbent can be reused.
It is also used sparingly in automotive refrigeration, and is seen as favorable for uses in domestic, commercial and industrial refrigeration and air conditioning systems. Carbon dioxide is also both plentiful and inexpensive. These factors have led to carbon dioxide being used as a refrigerant since 1850, when it was patented for use as a refrigerant in the United Kingdom.
Most often, the carbonate system is plotted, where the polyprotic acid is carbonic acid (a diprotic acid), and the different species are dissolved carbon dioxide, carbonic acid, bicarbonate, and carbonate. In acidic conditions, the dominant form is CO2; in basic (alkaline) conditions, the dominant form is CO2−3; and in between, the dominant form is HCO−3. At every pH, the concentration of carbonic acid is assumed to be negligible compared to the concentration of dissolved CO2, and so is often omitted from Bjerrum plots. These plots are very helpful in solution chemistry and natural water chemistry. In the example given here, it illustrates the response of seawater pH and carbonate speciation due to the input of man-made CO2 emission by the fossil fuel combustion.The Bjerrum plots for other polyprotic acids, including silicic, boric, sulfuric and phosphoric acids, are other commonly used examples.
|
What form when a single atom gains or loses electrons?
|
[
"fusional ions",
"vacuoles ions",
"carbon atoms",
"monatomic ions"
] |
D
|
Monatomic ions form when a single atom gains or loses electrons. For the main group elements, cations are generally formed by removing all of the valence electrons from the atom. Since the numbers of valence electrons for the representative elements are constant within a particular group, all we need is the group number of a given element to know its charge when it becomes a cation. Group 1 elements form ions with a 1+ charge, Group 2 metal ions have a 2+ charge, and the ions of Group 13 elements tend to have a 3+ charge. Heavier p-block metals such as tin and lead are special cases and will be discussed with the transition metal ions. The name of a monatomic cation is the same as the name of the neutral element. For example, the sodium atom (Na) loses a single electron to form the sodium ion (Na + ), while Al 3+ is an aluminum ion.
Removal of the electron gives a cation (left), whereas addition of an electron gives an anion (right). The hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation. Hydrogen forms the only cation that has no electrons, but even cations that (unlike hydrogen) still retain one or more electrons are still smaller than the neutral atoms or molecules from which they are derived.
Atoms are the smallest neutral particles into which matter can be divided by chemical reactions. An atom consists of a small, heavy nucleus surrounded by a relatively large, light cloud of electrons. An atomic nucleus typically consists of 1 or more protons and 0 or more neutrons. Protons and neutrons are, in turn, made of quarks.
In a simplistic one-electron model described below, the total energy of an electron is a negative inverse quadratic function of the principal quantum number n, leading to degenerate energy levels for each n > 1. In more complex systems—those having forces other than the nucleus–electron Coulomb force—these levels split. For multielectron atoms this splitting results in "subshells" parametrized by ℓ. Description of energy levels based on n alone gradually becomes inadequate for atomic numbers starting from 5 (boron) and fails completely on potassium (Z = 19) and afterwards.
Substances composed of discrete molecules or single atoms are held together by weaker attractive forces between the molecules, such as the London dispersion force: as electrons move within the molecules, they create momentary imbalances of electrical charge, which induce similar imbalances on nearby molecules and create synchronised movements of electrons across many neighbouring molecules.The more electropositive atoms, however, tend to instead lose electrons, creating a "sea" of electrons engulfing cations. The outer orbitals of one atom overlap to share electrons with all its neighbours, creating a giant structure of molecular orbitals extending over all the atoms. This negatively charged "sea" pulls on all the ions and keeps them together in a metallic bond.
The combination of two phenomena gives rise to metallic bonding: delocalization of electrons and the availability of a far larger number of delocalized energy states than of delocalized electrons. The latter could be called electron deficiency.
|
In earthworms, the skin serves as what type of organ?
|
[
"kidney",
"reproductive",
"excretory",
"respiratory"
] |
D
|
On hatching, each larva is surrounded by an integumentary envelope and has a large, rounded head, fully formed fins, and eyes with double notches. As the larva develops into a juvenile, this envelope fuses with the skin.This fish is preyed on by larger fish and sea birds.
In zoology, the epidermis is an epithelium (sheet of cells) that covers the body of a eumetazoan (animal more complex than a sponge). Eumetazoa have a cavity lined with a similar epithelium, the gastrodermis, which forms a boundary with the epidermis at the mouth.Sponges have no epithelium, and therefore no epidermis or gastrodermis. The epidermis of a more complex invertebrate is just one layer deep, and may be protected by a non-cellular cuticle. The epidermis of a higher vertebrate has many layers, and the outer layers are reinforced with keratin and then die. == References ==
Nematodes are very small, slender worms: typically about 5 to 100 µm thick, and 0.1 to 2.5 mm long. The smallest nematodes are microscopic, while free-living species can reach as much as 5 cm (2 in), and some parasitic species are larger still, reaching over 1 m (3 ft) in length. : 271 The body is often ornamented with ridges, rings, bristles, or other distinctive structures.The head of a nematode is relatively distinct. Whereas the rest of the body is bilaterally symmetrical, the head is radially symmetrical, with sensory bristles and, in many cases, solid 'head-shields' radiating outwards around the mouth.
This extra-stomachal digestion is not unlike that which Darwin had previously described as occurring in Insectivorous Plants. The structure and physiology of the calciferous glands of earthworms are described. Many hypotheses had been advanced for their function; Darwin believed them to be primarily for excretion and secondarily a digestion aid.
When a host has been located, the nematodes penetrate into the insect body cavity, usually via natural body openings (mouth, anus, spiracles) or areas of thin cuticle. (Shapiro-Ilan, David I., and Randy Gaugler. "Nematodes.")
|
Catalytic converters used on motor vehicles break down pollutants in what, yielding non-toxic compounds?
|
[
"muffler",
"intake",
"oil",
"exhaust"
] |
D
|
Catalytic converters are used on motor vehicles. They break down pollutants in exhaust to non-toxic compounds. For example, they change nitrogen oxides to harmless nitrogen and oxygen gases.
Further chemicals released are benzene and 1,3-butadiene that are also hazardous air pollutants. Increasing the amount of air in the engine reduces emissions of incomplete combustion products, but also promotes reaction between oxygen and nitrogen in the air to produce nitrogen oxides (NOx). NOx is hazardous to both plant and animal health, and leads to the production of ozone (O3).
In addition to enabling electronic fuel injection to work efficiently, this emissions control technique can reduce the amounts of both unburnt fuel and oxides of nitrogen entering the atmosphere. Unburnt fuel is pollution in the form of air-borne hydrocarbons, while oxides of nitrogen (NOx gases) are a result of combustion chamber temperatures exceeding 1300 kelvins, due to excess air in the fuel mixture thereby contributing to smog and acid rain. Volvo was the first automobile manufacturer to employ this technology in the late 1970s, along with the three-way catalyst used in the catalytic converter.
Transporting and storing hydrogen may also create pollutants. Fuel cells have been used in various kinds of vehicles including forklifts, especially in indoor applications where their clean emissions are important to air quality, and in space applications.
Exposures have been linked with acute short-term symptoms such as headache, dizziness, light-headedness, nausea, coughing, difficult or labored breathing, tightness of chest, and irritation of the eyes, nose, and throat. Long-term exposures can lead to chronic, more serious health problems such as cardiovascular disease, cardiopulmonary disease, and lung cancer. Elemental carbon attributable to traffic was significantly associated with wheezing at age 1 and persistent wheezing at age 3 in the Cincinnati Childhood Allergy and Air Pollution Study birth cohort study.The NERC-HPA funded Traffic Pollution and Health in London project at King's College London is currently seeking to refine understanding of the health effects of traffic pollution. Ambient traffic-related air pollution was associated with decreased cognitive function in older men.Mortality from diesel soot exposure in 2001 was at least 14,400 out of the German population of 82 million, according to the official report 2352 of the Umweltbundesamt Berlin (Federal Environmental Agency of Germany).The study of nanoparticles and nanotoxicology is in its infancy, and health effects from nanoparticles produced by all types of diesel engines are still being uncovered.
The transportation of fuel by trucks on winter roads impacts the environment negatively through high greenhouse gas emissions from the vehicles. Fuel spills may take place while the fuel is being transported and stored, posing environmental risks. Fuel tank leaks contaminate soil and groundwater. Generators can be noisy and disruptive, especially in quiet, remote communities. Emissions from diesel generators could contribute to health problems in community members.The environmental impacts of the systems used in off-grid buildings must also be considered due to embodied energy, embodied carbon, choice and source of materials, which can contribute to world issues such as climate change, air, water, and soil pollution, resource depletion and more.
|
Processing of filtrate in the proximal tubule helps maintain what level in body fluid?
|
[
"homeostasis",
"ph",
"temperature",
"metabolic level"
] |
B
|
In renal physiology, the filtration fraction is the ratio of the glomerular filtration rate (GFR) over the renal plasma flow (RPF). Filtration Fraction, FF = GFR/RPF, or F F = G F R R P F {\displaystyle FF={\frac {GFR}{RPF}}} . The filtration fraction, therefore, represents the proportion of the fluid reaching the kidneys that passes into the renal tubules. It is normally about 20%.
In response, the fluid inside the tubules brings immunoglobulins from the immune system to fight the bacterial infection. At the same time, there is an increase of mineralization of the surrounding tubules. This results in a constriction of the tubules, which is an attempt to slow the bacterial progression.
Because the filtration fraction, which is the ratio of the glomerular filtration rate (GFR) to the renal plasma flow (RPF), has increased, there is less plasma fluid in the downstream peritubular capillaries. This in turn leads to a decreased hydrostatic pressure and increased oncotic pressure (due to unfiltered plasma proteins) in the peritubular capillaries. The effect of decreased hydrostatic pressure and increased oncotic pressure in the peritubular capillaries will facilitate increased reabsorption of tubular fluid.
The kidneys in aves are divided into units called lobules. Within each lobule are numerous nephrons responsible for filtering blood. Arterial blood that is directed to the kidney enters the glomerulus under high pressure and leaks out in between the endothelial cells of the glomerular capillaries into Bowman’s capsules. The blood plasma filtrate contains waste along with non-waste essentials like glucose and ions. Once the filtrate enters the proximal tubule reabsorption of metabolically useful molecules into the blood begins.
The osmoregulatory system is interconnected with the circulatory system to permit effective regulation of salt and water balance. Circulatory fluids function in renal clearance, which is the blood volume that substances are removed from within the kidneys during a certain time period. In addition to filtration, the circulatory system also plays a role in reabsorption. Furthermore, the role of the renal portal system is to regulate renal hemodynamics during times of decreased arterial blood pressure.Kidneys of common ravens receive arterial and afferent venous blood and are drained by efferent veins.
|
What helps represent age-sex structure of the population?
|
[
"population pyramid",
"habitat chart",
"density graph",
"biome model"
] |
A
|
The age-sex structure of a population is the number of individuals of each sex and age in the population. Age-sex structure influences population growth. It is represented by a population pyramid. The number of survivors at each age is plotted on a survivorship curve.
Several studies have examined human birth sex ratio data to determine whether there is a natural relationship between the age of the mother or father and the birth sex ratio. For example, Ruder has studied 1.67 million births in 33 states in the United States to investigate the effect of parents' ages on birth sex ratios. Similarly, Jacobsen et al. have studied 820,000 births in Denmark with the same goal. These scientists find that maternal age has no statistically significant role on the human birth sex ratio.
In contrast, biodemographers embraced research programs expressly designed to study individuals at ages beyond their reproductive years because information on these age classes will shed important light on longevity and aging. The biological and demographic components of biodemography are not hierarchical but reciprocal in that both are primary windows on the world and are thus synergistic, complementary and mutually informing. However, there has been much more synthesis between the approaches to demographic research in recent years, such that collaboration between evolutionary, ecology and demographic researchers is increasingly common.
The change in total population over a period is equal to the number of births, minus the number of deaths, plus or minus the net amount of migration in a population. The number of births can be projected as the number of females at each relevant age multiplied by the assumed fertility rate. The number of deaths can be projected as the sum of the numbers of each age and sex in the population multiplied by their respective mortality rates. For many centuries, the overall population of the world changed relatively slowly: very broadly, the numbers of births were balanced by numbers of deaths (including high rates of infant immortality).
For example, if a female was much older but retained these “youthful” features, males may find her more favorable over other females who look their biological age. Beyond the face value of what males find physically attractive, secondary sexual characteristics related to body shape are factored in so adults may be able to recognize other adults from juveniles.
It emphasizes people's associations throughout the lifetime between group members and stereotype and status content. Even then, it does not deal with "nurture" in the sense of one's upbringing (by parents, relatives, etc.) but more in the sense of the culture that one grows up in. How do we "get" gender?
|
Large viruses began as what type of cells inside bigger host cells?
|
[
"symbiotic",
"static",
"parasitic",
"simple"
] |
C
|
Large viruses were once parasitic cells inside bigger host cells. Over time, genes needed to survive and reproduce outside host cells were lost.
The genetic material within virus particles, and the method by which the material is replicated, varies considerably between different types of viruses. DNA viruses The genome replication of most DNA viruses takes place in the cell's nucleus. If the cell has the appropriate receptor on its surface, these viruses enter the cell either by direct fusion with the cell membrane (e.g., herpesviruses) or—more usually—by receptor-mediated endocytosis. Most DNA viruses are entirely dependent on the host cell's DNA and RNA synthesising machinery and RNA processing machinery.
A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells.
This different mode of transfer differentiates it from total and subtotal destruction and causes the characteristic localized effects. Initially, host cells become enlarged, rounded, and refractile. Eventually, the host cells detach from the surface. The spreading of the virus occurs concentrically, so that the cells lifting off are surrounded by enlarged, rounded cells that are surrounded by healthy tissue. This type of CPE is characteristic of herpesviruses and poxviruses.
Viruses are introduced into neuronal tissue in many different ways. There are two major methods to introduce tracers into the target tissues.
Mimivirus is one of the largest characterised viruses, with a capsid diameter of 400 nm. Protein filaments measuring 100 nm project from the surface. The capsid appears hexagonal under an electron microscope, therefore the capsid is probably icosahedral.
|
How can you calculate the density of matter?
|
[
"by dividing its mass by its volume",
"by subtracting mass from volume",
"by multiplying its mass by its volume",
"by dividing its volume by its mass"
] |
A
|
The density of matter can be calculated by dividing its mass by its volume.
: 59–62 Mass densityThe density (more precisely, the volumetric mass density; also known as specific mass), of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume: ρ = m V {\displaystyle \rho ={\frac {m}{V}}} where ρ is the density, m is the mass, and V is the volume.
Assuming the mass of ordinary matter is about 1.45×1053 kg as discussed above, and assuming all atoms are hydrogen atoms (which are about 74% of all atoms in the Milky Way by mass), the estimated total number of atoms in the observable universe is obtained by dividing the mass of ordinary matter by the mass of a hydrogen atom. The result is approximately 1080 hydrogen atoms, also known as the Eddington number.
Density of states is the number of states per volume unit in an interval of energy (E, E + dE) that are available to be occupied by electrons. Both phonons and photons are bosons and thus, they obey Bose–Einstein statistics. This means that, since bosons with the same energy can occupy the same place in space, phonons and photons are force carrier particles and they have integer spins.
This gives a critical density of 0.85×10−26 kg/m3, or about 5 hydrogen atoms per cubic metre. This density includes four significant types of energy/mass: ordinary matter (4.8%), neutrinos (0.1%), cold dark matter (26.8%), and dark energy (68.3%). Although neutrinos are Standard Model particles, they are listed separately because they are ultra-relativistic and hence behave like radiation rather than like matter.
The density of matter in the interstellar medium can vary considerably: the average is around 106 particles per m3, but cold molecular clouds can hold 108–1012 per m3.A number of molecules exist in interstellar space, as can tiny 0.1 μm dust particles. The tally of molecules discovered through radio astronomy is steadily increasing at the rate of about four new species per year.
|
Frogs and toads have long back legs which are specialized for what action?
|
[
"flying",
"swimming",
"sprinting",
"jumping"
] |
D
|
Frogs The frog order also includes toads. Unlike other amphibians, frogs and toads lack a tail by adulthood. Their back legs are also longer because they are specialized for jumping. Frogs can jump as far as 20 times their body length. That’s like you jumping more than the length of a basketball court! red-eyed tree frog.
The tail is used in courtship and as a storage organ for proteins and lipids. It also functions as a defense against predation, when it may be lashed at the attacker or autotomised when grabbed. Unlike frogs, an adult salamander is able to regenerate limbs and its tail when these are lost.
Common frogs have an important place in human ecology by controlling the insect populations. In particular, their consumption of mosquitos and other crop-damaging insects has been especially valuable. In addition, Rana temporaria, due to their ecological pervasiveness and relative abundance, have become a common laboratory specimen.
In the early days of electrical research, a common method of detecting electric current was by means of a frog's leg galvanoscope. A good supply of live frogs was kept to hand by the researcher ready to have their legs prepared for the galvanoscope. Frogs were therefore a convenient material to use in other experiments. They were small, easily handled, the legs were especially sensitive to electric current, and they carried on responding longer than other animal candidates for this role.
A relatively few animals use five limbs for locomotion. Prehensile quadrupeds may use their tail to assist in locomotion and when grazing, the kangaroos and other macropods use their tail to propel themselves forward with the four legs used to maintain balance. Insects generally walk with six legs—though some insects such as nymphalid butterflies do not use the front legs for walking.
The most diverse group of animals on earth, the insects, are included in a larger taxon known as hexapods, most of which are hexapedal, walking and standing on six legs. Exceptions among the insects include praying mantises and water scorpions, which are quadrupeds with their front two legs modified for grasping, some butterflies such as the Lycaenidae (blues and hairstreaks) which use only four legs, and some kinds of insect larvae that may have no legs (e.g., maggots), or additional prolegs (e.g., caterpillars). Spiders and many of their relatives move on eight legs – they are octopedal.
|
Different regions of the cerebral cortex can be associated with particular functions, a concept known as what?
|
[
"reversal of function",
"localization of function",
"expressiveness of function",
"cytoplasm of function"
] |
B
|
Different regions of the cerebral cortex can be associated with particular functions, a concept known as localization of function. In the early 1900s, a German neuroscientist named Korbinian Brodmann performed an extensive study of the microscopic anatomy—the cytoarchitecture—of the cerebral cortex and divided the cortex into 52 separate regions on the basis of the histology of the cortex. His work resulted in a system of classification known as Brodmann’s areas, which is still used today to describe the anatomical distinctions within the cortex (Figure 13.8). The results from Brodmann’s work on the anatomy align very well with the functional differences within the cortex. Areas 17 and 18 in the occipital lobe are responsible for primary visual perception. That visual information is complex, so it is processed in the temporal and parietal lobes as well. The temporal lobe is associated with primary auditory sensation, known as Brodmann’s areas 41 and 42 in the superior temporal lobe. Because regions of the temporal lobe are part of the limbic system, memory is an important function associated with that lobe. Memory is essentially a sensory function; memories are recalled sensations such as the smell of Mom’s baking or the sound of a barking dog. Even memories of movement are really the memory of sensory feedback from those movements, such as stretching muscles or the movement of the skin around a joint. Structures in the temporal lobe.
The word neuroscience itself arises from this program.Paul Broca associated regions of the brain with specific functions, in particular language in Broca's area, following work on brain-damaged patients. John Hughlings Jackson described the function of the motor cortex by watching the progression of epileptic seizures through the body. Carl Wernicke described a region associated with language comprehension and production.
Its neuron cell bodies, dendrites, synapses, axons, and axon terminals play a crucial role in consciousness. The two hemispheres are divided into four lobes, distinct sections of the organ: the frontal lobe, parietal lobe, temporal lobe, and occipital lobe. Our understanding of the specific functions of the cerebral cortex are based on the theories of localisation and lateralisation.
A study by MIT shows that subset regions of the IT cortex are in charge of different objects. By selectively shutting off neural activity of many small areas of the cortex, the animal gets alternately unable to distinguish between certain particular pairments of objects. This shows that the IT cortex is divided into regions that respond to different and particular visual features.
Historically, the executive functions have been seen as regulated by the prefrontal regions of the frontal lobes, but it is still a matter of ongoing debate if that really is the case. Even though articles on prefrontal lobe lesions commonly refer to disturbances of executive functions and vice versa, a review found indications for the sensitivity but not for the specificity of executive function measures to frontal lobe functioning. This means that both frontal and non-frontal brain regions are necessary for intact executive functions. Probably the frontal lobes need to participate in basically all of the executive functions, but they are not the only brain structure involved.Neuroimaging and lesion studies have identified the functions which are most often associated with the particular regions of the prefrontal cortex and associated areas.
The piriform cortex, or pyriform cortex, is a region in the brain, part of the rhinencephalon situated in the cerebrum. The function of the piriform cortex relates to the sense of smell.
|
What is the term for a change in the inherited traits of organisms over time?
|
[
"evolution",
"mutation",
"emergence",
"generation"
] |
A
|
Darwin proposed the theory of evolution by natural selection. Evolution is a change in the inherited traits of organisms over time. Natural selection is the process by which living things with beneficial traits produce more offspring, so their traits become more common over time.
When analyzing the types of changes that can occur to a phenotype, we can see changes that are behavioral, morphological, or physiological. A characteristic of the phenotype that arises through adaptive maternal effects, is the plasticity of this phenotype. Phenotypic plasticity allows organisms to adjust their phenotype to various environments, thereby enhancing their fitness to changing environmental conditions. Ultimately it is a key attribute to an organism's, and a population's, ability to adapt to short term environmental change.Phenotypic plasticity can be seen in many organisms, one species that exemplifies this concept is the seed beetle Stator limbatus.
As Bateman and Dimichele say " the alternation of generations has become a terminological morass; often, one term represents several concepts or one concept is represented by several terms. "Possible variations are: Relative importance of the sporophyte and the gametophyte.
However, if the change has a positive influence, the mutation may become more and more common in a population until it becomes a fixed genetic piece of that population. Organisms changing via these two options comprise the classic view of natural selection.
Epigenetic inheritance may only affect fitness if it predictably alters a trait under selection. Evidence has been forwarded that environmental stimuli are important agents in the alteration of epigenes. Ironically, Darwinian evolution may act on these neo-Lamarckian acquired characteristics as well as the cellular mechanisms producing them (e.g. methyltransferase genes). Epigenetic inheritance may confer a fitness benefit to organisms that deal with environmental changes at intermediate timescales.
Another theory that had some support at that time was the inheritance of acquired characteristics: the belief that individuals inherit traits strengthened by their parents. This theory (commonly associated with Jean-Baptiste Lamarck) is now known to be wrong—the experiences of individuals do not affect the genes they pass to their children. Other theories included Darwin's pangenesis (which had both acquired and inherited aspects) and Francis Galton's reformulation of pangenesis as both particulate and inherited.
|
What type of diseases do antibiotics not affect?
|
[
"autoimmune diseases",
"viruses",
"cancer",
"animal stings"
] |
B
|
Viruses are not affected by antibiotics. Several viral diseases can be treated with antiviral drugs or prevented with vaccines.
Factors such as age and immune system condition may influence disease susceptibility, which could impact the severity of disease. If the individual becomes ill and needs medical attention, a physician may prescribe an antibiotic. This pathway depends on the medical doctor’s ability to identify potential antibiotic resistance before prescribing treatment to a patient affected by food-borne illness. If the bacteria causing the illness is resistant to the drug the physician recommended, then the illness will not be improved by the medication. This could potentially lead to increased morbidity and mortality.
Treatment depends on the type of opportunistic infection, but usually involves different antibiotics.
Though an effective antibiotic when all others fail, against extremely drug resistant infections, it has many side effects. including inhibition of monoamine oxidase, and as with other nitrofurans generally, minimum inhibitory concentrations also produce systemic toxicity: tremors, convulsions, peripheral neuritis, gastrointestinal disturbances, depression of spermatogenesis. Nitrofurans are recognized by FDA as mutagens/carcinogens, and can no longer be used since 1991.
Side effects are the same as per the individual components, with stomach or bowel upset from the flucloxacillin being the most common. Effects on the kidney or blood count may occur.Both parts are members of the penicillin family of antibiotics, so should not be taken by people allergic to penicillin. The combination is contraindicated in people with a history of flucloxacillin-associated jaundice/hepatic dysfunction and in people with porphyria.It is given cautiously to people with glandular fever, cytomegalovirus infection, acute lymphocytic leukaemia or chronic lymphocytic leukaemia; who may have an increased chance of rashes.
Bacterial infections are usually treated with antibiotics. However, the antibiotic sensitivities of different strains of E. coli vary widely. As gram-negative organisms, E. coli are resistant to many antibiotics that are effective against gram-positive organisms. Antibiotics which may be used to treat E. coli infection include amoxicillin, as well as other semisynthetic penicillins, many cephalosporins, carbapenems, aztreonam, trimethoprim-sulfamethoxazole, ciprofloxacin, nitrofurantoin and the aminoglycosides.Antibiotic resistance is a growing problem.
|
Which system carries out long-distance transport of materials between the root and shoot systems?
|
[
"circulatory tissue system",
"vascular tissue system",
"reproductive tissue system",
"perceptual tissue system"
] |
B
|
Allan gives the example of a leaf fallen into a stream. First, the soluble chemicals are dissolved and leached from the leaf upon its saturation with water. This adds to the DOM load in the system.
These pathways consist of cavities of the vessels, fibres, ray cells, pit chambers and their pit membrane openings, intercellular spaces and transitory cell wall passageways. Movement of water takes place in these passageways in any direction, longitudinally in the cells, as well as laterally from cell to cell until it reaches the lateral drying surfaces of the wood. The higher longitudinal permeability of sapwood of hardwood is generally caused by the presence of vessels.
For larger caliper trees and shrubs after their root balls are harvested from the ground, they are contained using techniques such as ball and burlap or wire baskets. This difference in production style will result in a root ball that is often larger, less sturdy, and less prone to girdling roots than a root ball of a container-grown plant however there is a longer recovery time for these larger plants based on the larger amount of lost root material at the time of harvest. == References ==
The phloem and xylem are parallel to each other, but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch (ramify) to form veins which supply as much of the leaf as possible, ensuring that cells carrying out photosynthesis are close to the transportation system.Typically leaves are broad, flat and thin (dorsiventrally flattened), thereby maximising the surface area directly exposed to light and enabling the light to penetrate the tissues and reach the chloroplasts, thus promoting photosynthesis. They are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications.
It has been suggested that such transport is mediated by interactions with proteins localized on the desmotubule, and/or by chaperones partially unfolding proteins, allowing them to fit through the narrow passage. A similar mechanism may be involved in transporting viral nucleic acids through the plasmodesmata.A number of mathematical models have been suggested for estimating transport across plasmodesmata. These models have primarily treated transport as a diffusion problem with some added hindrance.
|
How do reptiles typically reproduce?
|
[
"sexually",
"cloning",
"live birth",
"asexually"
] |
A
|
Reptiles typically reproduce sexually and lay eggs.
This unique mode of reproduction has been termed kleptogenesis by Bogart and colleagues. This is in contrast to hybridogenesis, where the maternal genomes are passed hemiclonally and the paternal genome is discarded every generation before the egg matures and reacquired from the sperm of another species. The nuclear DNA of the unisexuals generally comprises genomes from up to five species: the blue-spotted salamander (A. laterale), Jefferson salamander (A. jeffersonianum), small-mouthed salamander (A. texanum), streamside salamander (A. barbouri), and tiger salamander (A. tigrinum), denoted respectively as L, J, Tx, B, and Ti.
A case has been documented of a Komodo dragon reproducing via sexual reproduction after a known parthenogenetic event, highlighting that these cases of parthenogenesis are reproductive accidents, rather than adaptive, facultative parthenogenesis.Some reptile species use a ZW chromosome system, which produces either males (ZZ) or females (ZW). Until 2010, it was thought that the ZW chromosome system used by reptiles was incapable of producing viable WW offspring, but a (ZW) female boa constrictor was discovered to have produced viable female offspring with WW chromosomes.Parthenogenesis has been studied extensively in the New Mexico whiptail in the genus Aspidoscelis of which 15 species reproduce exclusively by parthenogenesis. These lizards live in the dry and sometimes harsh climate of the southwestern United States and northern Mexico.
Some reptiles use the ZW sex-determination system, which produces either males (with ZZ sex chromosomes) or females (with ZW or WW sex chromosomes). Until 2010, it was thought that the ZW chromosome system used by reptiles was incapable of producing viable WW offspring, but a (ZW) female boa constrictor was discovered to have produced viable female offspring with WW chromosomes. The female boa could have chosen any number of male partners (and had successfully in the past) but on this occasion she reproduced asexually, creating 22 female babies with WW sex-chromosomes.
The female finds a suitable location to lay her eggs, usually in a rotting log or similarly damp area, and deposits them without any further parental care. Young females will only produce one clutch of three to sixteen eggs, while a large female can produce up to four. The eggs take approximately ten weeks to hatch and emerge near the end of summer. The young lizards grow quickly and are able to reproduce the next year.
At some point, the growing egg or offspring must be expelled. There are several possible modes of reproduction. These are traditionally classified as follows: Oviparity, as in most invertebrates and reptiles, monotremes, dinosaurs and all birds which lay eggs that continue to develop after being laid, and hatch later. Viviparity, as in almost all mammals (such as whales, kangaroos and humans) which bear their young live.
|
All organisms must adapt to what in order to survive?
|
[
"natural",
"weather",
"conditions",
"environment"
] |
D
|
All organisms must adapt to their environment in order to survive. This is true whether they live in water or on land. Most environments are not as extreme as the deep ocean where tube worms live. But they all have conditions that require adaptations. In this chapter, you will read about a wide variety of environments and the organisms that live in them.
However, given that organisms are integrated systems, rather than mechanical aggregates of parts, this is not always the case. For example, the need to avoid predators may constrain foragers to feed less than the optimal rate.
The organisms are preserved in good condition and shape. The diversity and number of co-inclusions help to draw conclusions about mutual relations and co-existence. == References ==
Involving evolutionary physiology and environmental physiology, comparative physiology considers the diversity of functional characteristics across organisms.
Such genes may be essential but only present in the host organism. For instance, Chlamydia trachomatis cannot synthesize purine and pyrimidine nucleotides de novo, so these bacteria are dependent on the nucleotide biosynthetic genes of the host.Another kind of metabolic dependency, unrelated to cross-species interactions, can be found when bacteria are grown under specific nutrient conditions. For example, more than 100 genes become essential when Escherichia coli is grown on nutrient-limited media.
Organisms also evolve while adapting - even thriving - in a benign environment (for example, a marine sponge modifies its structure in response to current changes, in order to better absorb and process nutrients). Self-preservation is therefore an almost universal hallmark of life. However, when introduced to a novel threat, many species will have a self-preservation response either too specialised, or not specialised enough, to cope with that particular threat. An example is the dodo, which evolved in the absence of natural predators and hence lacked an appropriate, general self-preservation response to heavy predation by humans and rats, showing no fear of them.
|
Biochemical compounds that include sugars, starches, and cellulose are examples of what?
|
[
"electrolytes",
"lipids",
"carbohydrates",
"proteins"
] |
C
|
Carbohydrates are biochemical compounds that include sugars, starches, and cellulose. They contain carbon, hydrogen, and oxygen, and they are used mainly for energy by living things.
In this cell-free biosystem, beta-1,4-glycosidic bond-linked cellulose is partially hydrolyzed to cellobiose. Cellobiose phosphorylase cleaves to glucose 1-phosphate and glucose; the other enzyme—potato alpha-glucan phosphorylase can add a glucose unit from glucose 1-phosphorylase to the non-reducing ends of starch.
Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Some, such as the raffinose series, occur as storage or transport carbohydrates in plants. Others, such as maltodextrins or cellodextrins, result from the microbial breakdown of larger polysaccharides such as starch or cellulose.
However, some biological substances commonly called "monosaccharides" do not conform to this formula (e.g. uronic acids and deoxy-sugars such as fucose) and there are many chemicals that do conform to this formula but are not considered to be monosaccharides (e.g. formaldehyde CH2O and inositol (CH2O)6).The open-chain form of a monosaccharide often coexists with a closed ring form where the aldehyde/ketone carbonyl group carbon (C=O) and hydroxyl group (–OH) react forming a hemiacetal with a new C–O–C bridge. Monosaccharides can be linked together into what are called polysaccharides (or oligosaccharides) in a large variety of ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is a modified version of ribose; chitin is composed of repeating units of N-acetyl glucosamine, a nitrogen-containing form of glucose.
A portion of organic matter is not mineralized and instead decomposed into stable organic matter that is denominated "humus".The decomposition of organic compounds occurs at very different rates, depending on the nature of the compound. The ranking, from fast to slow rates, is: Sugars, starches, and simple proteins Proteins Hemicelluloses Cellulose Lignins and fatsThe reactions that occur can be included in one of 3 genera: Enzymatic oxidation that produces carbon dioxide, water, and heat.
The difference between cellulose and other complex carbohydrate molecules is how the glucose molecules are linked together. In addition, cellulose is a straight chain polymer, and each cellulose molecule is long and rod-like. This differs from starch, which is a coiled molecule. A result of these differences in structure is that, compared to starch and other carbohydrates, cellulose cannot be broken down into its glucose subunits by any enzymes produced by animals.
|
What emerges from an insect egg?
|
[
"cocoon",
"larva",
"fungi",
"parasite"
] |
B
|
When an insect egg hatches, a larva emerges. The larva eats and grows and then enters the pupa stage. The pupa is immobile and may be encased in a cocoon . During the pupa stage, the insect goes through metamorphosis . Tissues and appendages of the larva break down and reorganize into the adult form. How did such an incredible transformation evolve? Metamorphosis is actually very advantageous. It allows functions to be divided between life stages. Each stage can evolve adaptations to suit it for its specific functions without affecting the adaptations of the other stage.
The majority of insects hatch from eggs. The fertilization and development takes place inside the egg, enclosed by a shell (chorion) that consists of maternal tissue. In contrast to eggs of other arthropods, most insect eggs are drought resistant. This is because inside the chorion two additional membranes develop from embryonic tissue, the amnion and the serosa.
Females lay eggs in crevices in the wood or in the holes left by emerging beetles, The adults do not feed, and so die within a few weeks, by which time the female may have laid 40 to 80 eggs in small batches.The eggs hatch after about a month. The newly hatched larvae are tiny and chew their way into the timber, feeding on the wood. Their growth is slow and it may take from two to ten years, or even more, for them to reach their full size. At this stage they pupate in a chamber close to the wood surface, and either emerge through a newly created hole after twenty to thirty days, or else emerge in the following spring (about eleven months later).
The female of this beetle will lay eggs in any damp, decaying timber which has been attacked by fungus. The eggs are creamy white, slightly curved with tapered ends. The larvae, also creamy white, are equipped with brown mandibles, ready to bore into the timber and feed on the wood. The adult insects are around 10–12 mm in length, yellowish to reddish-orange, with a long slender body and antennae half its body length.
The eggs are normally laid on surface water and go through three distinct larval stages. The larvae are usually found in still or stagnant water, like water reservoirs or liquid dung. Just before the pupation stage, the larvae leave their aquatic environment.
Tent caterpillars are among the most social of larvae. The adult moth lays her eggs in a single batch in late spring or early summer. An egg mass contains about 200 to 300 eggs. Embryogenesis proceeds rapidly, and within three weeks, fully formed caterpillars can be found within the eggs.
|
What can protons and neutrons be broken down into?
|
[
"quarks",
"molecules",
"strings",
"ions"
] |
A
|
Today, scientists think that electrons truly are fundamental particles that cannot be broken down into smaller, simpler particles. They are a type of fundamental particles called leptons. Protons and neutrons, on the other hand, are no longer thought to be fundamental particles. Instead, they are now thought to consist of smaller, simpler particles of matter called quarks. Scientists theorize that leptons and quarks are held together by yet another type of fundamental particles called bosons. All three types of fundamental particles—leptons, quarks, and bosons—are described below. The following Figure below shows the variety of particles of each type.
But nuclei have a positive charge that repels other positively charged nuclei, and they are bound together tightly by a force that physicists were only just beginning to understand. To break them up, to disintegrate them, would require much higher energies, of the order of millions of volts. Lawrence saw that such a particle accelerator would soon become too long and unwieldy for his university laboratory.
In nuclear physics and particle physics, the strong interaction, which is also often called the strong force or strong nuclear force, is a fundamental interaction that confines quarks into proton, neutron, and other hadron particles. The strong interaction also binds neutrons and protons to create atomic nuclei, where it is called the nuclear force. Most of the mass of a common proton or neutron is the result of the strong interaction energy; the individual quarks provide only about 1% of the mass of a proton. At the range of 10−15 m (1 femtometer, slightly more than the radius of a nucleon), the strong force is approximately 100 times as strong as electromagnetism, 106 times as strong as the weak interaction, and 1038 times as strong as gravitation.The strong interaction is observable at two ranges and mediated by two force carriers.
Atoms are the smallest neutral particles into which matter can be divided by chemical reactions. An atom consists of a small, heavy nucleus surrounded by a relatively large, light cloud of electrons. An atomic nucleus typically consists of 1 or more protons and 0 or more neutrons. Protons and neutrons are, in turn, made of quarks.
However, at CERN, protons are accelerated in the Proton Synchrotron to an energy of 26 GeV and then smashed into an iridium rod. The protons bounce off the iridium nuclei with enough energy for matter to be created. A range of particles and antiparticles are formed, and the antiprotons are separated off using magnets in vacuum.
Soon after the Big Bang, primordial protons and neutrons formed from the quark–gluon plasma of the early universe as it cooled below two trillion degrees. A few minutes later, in a process known as Big Bang nucleosynthesis, nuclei formed from the primordial protons and neutrons. This nucleosynthesis formed lighter elements, those with small atomic numbers up to lithium and beryllium, but the abundance of heavier elements dropped off sharply with increasing atomic number.
|
What is the name of the stage of life when a child becomes sexually mature?
|
[
"adolescence",
"growth spurt",
"puberty",
"maturity"
] |
C
|
Puberty is the stage of life when a child becomes sexually mature. Puberty lasts from about 10 to 16 years of age in girls and from about 12 to 18 years of age in boys. In both girls and boys, puberty begins when the pituitary gland signals the gonads (ovaries or testes) to start secreting sex hormones (estrogen in girls, testosterone in boys). Sex hormones, in turn, cause many other changes to take place.
During the latency stage, the child's sexual interests are repressed. Stage five is the genital stage, which takes place from puberty until adulthood. During the genital stage, puberty begins to occur.
Growth spurts began at around 10–12, but markers of later stages of puberty such as menarche had delays that correlated with severe environmental conditions such as poverty, poor nutrition, air and pollution. Puberty that starts earlier than usual is known as precocious puberty, and puberty which starts later than usual is known as delayed puberty. Notable among the morphologic changes in size, shape, composition, and functioning of the pubertal body, is the development of secondary sex characteristics, the "filling in" of the child's body; from female to woman, from male to man. Derived from the Latin puberatum (age of maturity), the word puberty describes the physical changes to sexual maturation, not the psychosocial and cultural maturation denoted by the term adolescent development in Western culture, wherein adolescence is the period of mental transition from childhood to adulthood, which overlaps much of the body's period of puberty.
In modern industrial societies, a person, especially if educated, has the opportunity to begin entering the "first maturity" of the humanic "total individual" in his or her mid teens. However, according to Heard, a fifth stage is in the process of emerging, a post-individual psychological phase of persons and therefore of culture. According to Heard, the second maturity can be one that lies beyond "personal success, economic mastery, and the psychophysical capacity to enjoy life" (p.
These develop into mature females in about seven to ten days. The life span of an adult is about 30 days.Population densities are at their highest in early summer, then decrease through predation and parasitism. In autumn, the lengthening of the night triggers the production of a single generation of sexual individuals (males and oviparous females) by the same parthenogenetic parent females.
The second stage of psychosexual development is the anal stage, spanning from the age of eighteen months to three years, wherein the infant's erogenous zone changes from the mouth (the upper digestive tract) to the anus (the lower digestive tract), while the ego formation continues. Toilet training is the child's key anal-stage experience, occurring at about the age of two years, and results in conflict between the id (demanding immediate gratification) and the ego (demanding delayed gratification) in eliminating bodily wastes, and handling related activities (e.g. manipulating excrement, coping with parental demands). The style of parenting influences the resolution of the id–ego conflict, which can be either gradual and psychologically uneventful, or which can be sudden and psychologically traumatic.
|
What part of the brain is divided from front to back into the left and right hemispheres?
|
[
"cerebellum",
"medula oblongata",
"thalmus",
"cerebrum"
] |
D
|
The cerebrum is divided down the middle from the front to the back of the head. The two halves of the cerebrum are called the right and left hemispheres. The two hemispheres are very similar but not identical. They are connected to each other by a thick bundle of axons deep within the brain. These axons allow the two hemispheres to communicate with each other. Did you know that the right hemisphere of the cerebrum controls the left side of the body, and vice versa? This can happen because of the connections between the two hemispheres.
Rossi (1977) suggests that the function and characteristics between left and right cerebral hemispheres may enable us to locate the archetypes in the right cerebral hemisphere. He cites research indicating that left hemispherical functioning is primarily verbal and associational, and that of the right primarily visuospatial and apperceptive. Thus the left hemisphere is equipped as a critical, analytical, information processor while the right hemisphere operates in a 'gestalt' mode. This means that the right hemisphere is better at getting a picture of a whole from a fragment, is better at working with confused material, is more irrational than the left, and is more closely connected to bodily processes.
Its neuron cell bodies, dendrites, synapses, axons, and axon terminals play a crucial role in consciousness. The two hemispheres are divided into four lobes, distinct sections of the organ: the frontal lobe, parietal lobe, temporal lobe, and occipital lobe. Our understanding of the specific functions of the cerebral cortex are based on the theories of localisation and lateralisation.
The anterior limb of internal capsule (or frontal part) is situated between the lentiform nucleus and the caudate nucleus. It contains: thalamocortical fibers (passing from the lateral thalamic nuclei to the frontal lobe) corticothalamic fibres (passing from frontal lobe to the lateral thalamic nuclei) fibers connecting the caudate nucleus to the putamen (these fibres are transversely oriented) fibers connecting the cortex with the corpus striatum frontopontine fibers (passing from the frontal lobe through the medial fifth of the base of the cerebral peduncle to the nuclei pontis) thalamic pontine fibers
The idea that the two hemispheres of the brain may learn differently has virtually no grounding in neuroscience research. The idea has arisen from the knowledge that some cognitive skills appear differentially localised to a specific hemisphere (e.g., language functions are typically supported by left hemisphere brain regions in healthy right handed people). However, massive amount of fibre connections link the two hemispheres of the brain in neurologically healthy individuals. Every cognitive skill that has been investigated using neuroimaging to date employs a network of brain regions spread across both cerebral hemispheres, including language and reading, and thus no evidence exists for any type of learning that is specific to one side of the brain.
In neuroanatomy, the lateral sulcus (also called Sylvian fissure, after Franciscus Sylvius, or lateral fissure) is one of the most prominent features of the human brain. The lateral sulcus is a deep fissure in each hemisphere that separates the frontal and parietal lobes from the temporal lobe. The insular cortex lies deep within the lateral sulcus.
|
Because their cells are arranged in bundles, the appearance of skeletal and cardiac muscles is described as what?
|
[
"quadrant",
"cylindrical",
"incised",
"striated"
] |
D
|
http://zonalandeducation. com/mstm/physics/mechanics/vectors/introduction/introductionVectors. html.
Cardiac muscle is involuntary, striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. The cardiac muscle cells, (also called cardiomyocytes or myocardiocytes), predominantly contain only one nucleus, although populations with two to four nuclei do exist. The myocardium is the muscle tissue of the heart and forms a thick middle layer between the outer epicardium layer and the inner endocardium layer.
The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle is found in the walls of the uterus, bladder, intestines, stomach, oesophagus, respiratory airways, and blood vessels. Cardiac muscle is found only in the heart, allowing it to contract and pump blood round the body.
Each cardiomyocyte needs to contract in coordination with its neighboring cells - known as a functional syncytium - working to efficiently pump blood from the heart, and if this coordination breaks down then – despite individual cells contracting – the heart may not pump at all, such as may occur during abnormal heart rhythms such as ventricular fibrillation.Viewed through a microscope, cardiac muscle cells are roughly rectangular, measuring 100–150μm by 30–40μm. Individual cardiac muscle cells are joined at their ends by intercalated discs to form long fibers.
There are three distinct types of muscle: skeletal muscle, cardiac or heart muscle, and smooth (non-striated) muscle. Muscles provide strength, balance, posture, movement, and heat for the body to keep warm.There are approximately 640 muscles in an adult male human body. A kind of elastic tissue makes up each muscle, which consists of thousands, or tens of thousands, of small muscle fibers. Each fiber comprises many tiny strands called fibrils, impulses from nerve cells control the contraction of each muscle fiber.
Typically, cardiomyocytes have a single, central nucleus, but can also have two or more.Cardiac muscle cells branch freely and are connected by junctions known as intercalated discs which help the synchronized contraction of the muscle. The sarcolemma (membrane) from adjacent cells bind together at the intercalated discs. They consist of desmosomes, specialized linking proteoglycans, tight junctions, and large numbers of gap junctions that allow the passage of ions between the cells and help to synchronize the contraction.
|
What resource is considered nonrewable for human purposes, because it takes so long to form and is depleted by farming and other activities?
|
[
"water",
"soil",
"acid",
"sunshine"
] |
B
|
Although renewable, soil takes a very long to form—up to hundreds of millions of years. So, for human purposes, soil is a nonrenewable resource. It is also constantly depleted of nutrients through careless use and eroded by wind and water. For example, misuse of soil caused a huge amount of it to simply blow away in the 1930s during the Dust Bowl (see Figure below ). Soil must be used wisely to preserve it for the future. Conservation practices include contour plowing and terracing. Both reduce soil erosion. Soil also must be protected from toxic wastes.
Resource efficiency reflects the understanding that global economic growth and development can not be sustained at current production and consumption patterns. Globally, humanity extracts more resources to produce goods than the planet can replenish. Resource efficiency is the reduction of the environmental impact from the production and consumption of these goods, from final raw material extraction to the last use and disposal.
An item becomes a resource with time and developing technology. The benefits of resource utilization may include increased wealth, proper functioning of a system, or enhanced well-being. From a human perspective, a natural resource is anything obtained from the environment to satisfy human needs and wants.
This is particularly true during periods of increasing scarcity and shortages (depletion and overconsumption of resources). Resource extraction is also a major source of human rights violations and environmental damage. The Sustainable Development Goals and other international development agendas frequently focus on creating more sustainable resource extraction, with some scholars and researchers focused on creating economic models, such as circular economy, that rely less on resource extraction, and more on reuse, recycling and renewable resources that can be sustainably managed.
They argue that for every new mouth that demands resources for its nourishment, a brain and a pair of hands are also born, contributing to technological progress. In other words, contrary to what neo-Malthusians think, population is seen as a resource that far from causing problems solves them. Defense by the anthropocentric aesthetic value of resources rather than by their future value.
From a broader biological or ecological perspective, a resource satisfies the needs of a living organism (see biological resource).The concept of resources has been developed across many established areas of work, in economics, biology and ecology, computer science, management, and human resources for example - linked to the concepts of competition, sustainability, conservation, and stewardship. In application within human society, commercial or non-commercial factors require resource allocation through resource management. The concept of a resource can also be tied to the direction of leadership over resources, this can include the things leaders have responsibility for over the human resources, with management, help, support or direction such as in charge of a professional group, technical experts, innovative leaders, archiving expertise, academic management, association management, business management, healthcare management, military management, public administration, spiritual leadership and social networking administrator.
|
What in orange juice makes it taste sour?
|
[
"citric acid",
"amino acid",
"acetic acid",
"carbonation"
] |
A
|
Some solutions have special properties because they are acids. Orange juice is an example. It contains an acid called citric acid. It makes orange juice taste sour. Some solutions are bases rather than acids.
The taste of oranges is determined mainly by the relative ratios of sugars and acids, whereas orange aroma derives from volatile organic compounds, including alcohols, aldehydes, ketones, terpenes, and esters. Bitter limonoid compounds, such as limonin, decrease gradually during development, whereas volatile aroma compounds tend to peak in mid– to late–season development. Taste quality tends to improve later in harvests when there is a higher sugar/acid ratio with less bitterness. As a citrus fruit, the orange is acidic, with pH levels ranging from 2.9 to 4.0.Sensory qualities vary according to genetic background, environmental conditions during development, ripeness at harvest, postharvest conditions, and storage duration.
The fruit pulp can vary from sweet to extremely sour. Marmalade, a condiment derived from cooked orange or lemon, can be especially bitter, but is usually sweetened with sugar to cut the bitterness and produce a jam-like result. Lemon or lime is commonly used as a garnish for water, soft drinks, or cocktails.
Brewers of more common beer styles would ensure that no such bacteria are allowed to enter the fermenter. Other sour styles of beer include Berliner weisse, Flanders red and American wild ale.In winemaking, a bacterial process, natural or controlled, is often used to convert the naturally present malic acid to lactic acid, to reduce the sharpness and for other flavor-related reasons. This malolactic fermentation is undertaken by lactic acid bacteria. While not normally found in significant quantities in fruit, lactic acid is the primary organic acid in akebia fruit, making up 2.12% of the juice.
In orange juice, pulp is responsible for desirable flow properties, taste, flavor, and mouth feel. However, pulpy orange juice precipitates based on a rate dependent on the diameter, density, and viscosity of the suspended particles as well as the suspending juice. In order to remain suspended in orange juice, pulp particles must have appropriate particle size, charge, and specific gravity. Depending on type of processing method, the size of pulp particles ranges from 2–5 millimeters (0.08–0.2 in). Those that are smaller than 2 mm (0.08 in) are known to be more stable, so it is beneficial to reduce the size of particles by incorporating hydrocolloids to the juice product. Hydrocolloids would decrease the rate of sediment formation and decrease the falling rate of pulp particles.
The juice of the uppermost parts of the plant has an intensive green color; its pure flavor is bitter – hempy. The juice of the fibers and shives of the plant is lighter in color and tastes sweet. Hemp juice creates a distinct umami flavor, based on the multitude of proteins, polyphenols and cannabinoids in the hemp plant. The bitter taste of the hemp juice is transformed into a fresh and sweet flavor after mixing it with vegetable or fruit juices. Moreover, the original taste of fruits and vegetables may be highlighted with the use of hemp juice.
|
What scientist created the modern system for classifying organisms?
|
[
"Bohr",
"linnaeus",
"Newton",
"Pasteur"
] |
B
|
Linnaeus published his classification system in the 1700s. Since then, many new species have been discovered. The biochemistry of many organisms has also become known. Eventually, scientists realized that Linnaeus’s system of classification needed revision.
Historically, Aristotle divided animals into those with blood and those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa (now synonymous with Animalia) and the Protozoa, single-celled organisms no longer considered animals.
The history of model organisms began with the idea that certain organisms can be studied and used to gain knowledge of other organisms or as a control (ideal) for other organisms of the same species. Model organisms offer standards that serve as the authorized basis for comparison of other organisms. Model organisms are made standard by limiting genetic variance, creating, hopefully, this broad applicability to other organisms.The idea of the model organism first took root in the middle of the 19th century with the work of men like Charles Darwin and Gregor Mendel and their respective work on natural selection and the genetics of heredity. As the first model organisms were introduced into labs in the 20th century, these early efforts to identify standards to measure organisms against persisted. Beginning in the early 1900s Drosophila entered the research laboratories and opened up the doors for other model organisms like Tobacco mosaic virus, E. coli, C57BL/6 (lab mice), etc. These organisms have led to many advances in the past century.
The term physiology was introduced by the French physician Jean Fernel (1497–1558). In the 17th century, William Harvey (1578–1657) described the circulatory system, pioneering the combination of close observation with careful experiment. In the 19th century, physiological knowledge began to accumulate at a rapid rate with the cell theory of Matthias Schleiden and Theodor Schwann in 1838, that organisms are made up of cells.
The biological systematics and taxonomy of invertebrates as proposed by Richard C. Brusca and Gary J. Brusca in 2003 is a system of classification of invertebrates, as a way to classify animals without backbones.
These applications include: Studying the diversity of organisms and the differentiation between extinct and living creatures. Biologists study the well-understood relationships by making many different diagrams and "trees" (cladograms, phylogenetic trees, phylogenies, etc.). Including the scientific names of organisms, species descriptions and overviews, taxonomic orders, and classifications of evolutionary and organism histories.
|
What will be the effect to an organism if its homeostasis is not maintained?
|
[
"slow aging",
"weight regulation",
"death or disease",
"healthy mental state"
] |
C
|
All of the organ systems of the body work together to maintain homeostasis of the organism. If homeostasis fails, death or disease may result.
Organisms, when presented with the problem of regulating body temperature, have not only behavioural, physiological, and structural adaptations but also a feedback system to trigger these adaptations to regulate temperature accordingly. The main features of this system are stimulus, receptor, modulator, effector and then the feedback of the newly adjusted temperature to the stimulus. This cyclical process aids in homeostasis.
These repressive proteins are broken down when the host cell is under stress, resulting in the expression of the repressed phage genes. Stress can be from starvation, poisons (like antibiotics), or other factors that can damage or destroy the host. In response to stress, the activated prophage is excised from the DNA of the host cell by one of the newly expressed gene products and enters its lytic pathway.
Homeostasis was almost definitely a challenge for land invading vertebrates. Gas exchange and water balance are highly different in water and in air. Homeostasis mechanisms suitable for a terrestrial environment may have been necessary to develop before these organisms invaded land.
The lifecycle will then continue respectively. There are two theories contending to explain the majority of S. sclerotiorum virulence: The oxalate-dependent theory and the pH-dependent theory.
While most animals that go through winter dormancy lower their metabolic rates, some fish, such as the cunner, do not. Instead, they do not actively depress their base metabolic rate, but instead they simply reduce their activity level. Fish that undergo winter dormancy in oxygenated water survive via inactivity paired with the colder temperature, which decreases energy consumption, but not the base metabolic rate that their bodies consume. But for the Antarctic yellowbelly rockcod (Notothenia coriiceps) and for fish that undergo winter dormancy in hypoxic conditions, they do suppress their metabolism like other animals that are dormant in the winter. The mechanism for evolution of metabolic suppression in fish is unknown. Most fish that are dormant in the winters save enough energy by being still and so there is not a strong selective pressure to develop a metabolic suppression mechanism like that which is necessary in hypoxic conditions.
|
Since warmer molecules have more energy, they are more what?
|
[
"inactive",
"dense",
"active",
"abundant"
] |
C
|
The density of air varies from place to place. Air density depends on several factors. One is temperature. Like other materials, warm air is less dense than cool air. Since warmer molecules have more energy, they are more active. The molecules bounce off each other and spread apart. Another factor that affects the density of air is altitude.
Temperature usually has a major effect on the rate of a chemical reaction. Molecules at a higher temperature have more thermal energy. Although collision frequency is greater at higher temperatures, this alone contributes only a very small proportion to the increase in rate of reaction. Much more important is the fact that the proportion of reactant molecules with sufficient energy to react (energy greater than activation energy: E > Ea) is significantly higher and is explained in detail by the Maxwell–Boltzmann distribution of molecular energies.
However, the main reason that temperature increases the rate of reaction is that more of the colliding particles will have the necessary activation energy resulting in more successful collisions (when bonds are formed between reactants). The influence of temperature is described by the Arrhenius equation. For example, coal burns in a fireplace in the presence of oxygen, but it does not when it is stored at room temperature.
In physical chemistry, a hot atom is an atom that has a high kinetic or internal energy.When molecule AB adsorbs on a surface dissociatively, both A and B adsorb on the surface, or only A adsorbs on the surface, and B desorbs from the surface.In case 2, B gains a high translational energy from the adsorption energy of A, and hot atom B is generated. For example, the hydrogen molecule, because of its light mass, gets a high translational energy. Such a hot atom does not fly into vacuum but is trapped on the surface, where it diffuses with high energy.
Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, molecules begin to vibrate and move more, usually creating more distance between themselves. Substances which contract with increasing temperature are unusual, and only occur within limited temperature ranges (see examples below). The relative expansion (also called strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. As energy in particles increases, they start moving faster and faster, weakening the intermolecular forces between them and therefore expanding the substance.
Even though these motions are called "internal", the external portions of molecules still move—rather like the jiggling of a stationary water balloon. This permits the two-way exchange of kinetic energy between internal motions and translational motions with each molecular collision. Accordingly, as internal energy is removed from molecules, both their kinetic temperature (the kinetic energy of translational motion) and their internal temperature simultaneously diminish in equal proportions.
|
If only blue light strikes green leaves what happens to it?
|
[
"it causes heating",
"it is absorbed",
"it is reflected",
"it causes cooling"
] |
B
|
The color of light that strikes an object may also affect the color that the object appears. For example, if only blue light strikes green leaves, the blue light is absorbed and no light is reflected.
As blue and red light are absorbed, green light remains. Ocean regions with high concentrations of phytoplankton have shades of blue-to-green water depending on the amount and type of the phytoplankton.Green waters can also have a combination of phytoplankton, dissolved substances, and sediments, while still appearing green. This often happens in estuaries, coastal waters, and inland waters, which are called "optically complex" waters because multiple different substances are creating the green color seen by the sensor.
UVR8: UV-B light reception Cryptochrome: blue and UV-A light reception Phototropin: blue and UV-A light perception (to mediate phototropism and chloroplast movement) Zeitlupe: blue light entrainment of the circadian clock Phytochrome: red and far-red light receptionAll the photoreceptors listed above allow plants to sense light with wavelengths range from 280 nm (UV-B) to 750 nm (far-red light). Plants use light of different wavelengths as environmental cues to both alter their position and to trigger important developmental transitions. The most prominent wavelength responsible for plant mechanisms is blue light, which can trigger cell elongation, plant orientation, and flowering.
Many plants are fluorescent due to the presence of chlorophyll, which is probably the most widely-distributed fluorescent molecule, producing red emission under a range of excitation wavelengths. This attribute of chlorophyll is commonly used by ecologists to measure photosynthetic efficiency.The Mirabilis jalapa flower contains violet, fluorescent betacyanins and yellow, fluorescent betaxanthins. Under white light, parts of the flower containing only betaxanthins appear yellow, but in areas where both betaxanthins and betacyanins are present, the visible fluorescence of the flower is faded due to internal light-filtering mechanisms. Fluorescence was previously suggested to play a role in pollinator attraction, however, it was later found that the visual signal by fluorescence is negligible compared to the visual signal of light reflected by the flower.
Many factors can cause pigments to fade or "shift" over time, under the influence of the agents of deterioration detailed in the introductory sections above, leading to erroneous conclusions when colors have faded or been otherwise compromised over time. For instance, what may appear to the eye to read as an "olive green" through visual inspection alone but may actually be identified as Prussian blue in the laboratory. Likewise, the accumulation of particulate matter from smoke or fire may accumulate on painted walls or ceilings, and if left untreated, over time, may cast a yellow hue that is mistakenly accepted as part of the intended color scheme.
If the leaves are green and look healthy, the soil pH is normal and acceptable for plant life. But if the plant leaves have yellowing between the veins on their leaves, that means the plant is suffering from acidification and is unhealthy. Moreover, a plant suffering from soil acidification cannot photosynthesize. Drying out of the plant due to acidic water destroy chloroplast organelles. Without being able to photosynthesize a plant cannot create nutrients for its own survival or oxygen for the survival of aerobic organisms; which affects most species of Earth and ultimately end the purpose of the plants existence.
|
Which type of animal creates useful substances such as honey, wax, lacquer, and silk?
|
[
"insects",
"fungus",
"bacteria",
"spiders"
] |
A
|
Insects produce useful substances, such as honey, wax, lacquer, and silk.
Silk is a "natural" protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from cocoons made by the larvae of the silkworm Bombyx mori reared in captivity. Rearing of silks is called sericulture. Degummed fibers from B. mori are 5-10 μm in diameter.
Waxes are synthesized by many plants and animals. Those of animal origin typically consist of wax esters derived from a variety of fatty acids and carboxylic alcohols. In waxes of plant origin, characteristic mixtures of unesterified hydrocarbons may predominate over esters. The composition depends not only on species, but also on geographic location of the organism.
Textiles from the most utilitarian to the most luxurious are often made from non-human animal fibres such as wool, camel hair, angora, cashmere, and mohair. Hunter-gatherers have used non-human animal sinews as lashings and bindings. Leather from cattle, pigs and other species is widely used to make shoes, handbags, belts and many other items.
These substances found a variety of commercial applications, such as candles, soap, cosmetics, machine oil, other specialized lubricants, lamp oil, pencils, crayons, leather waterproofing, rustproofing materials, and many pharmaceutical compounds. Ambergris, a solid, waxy, flammable substance produced in the digestive system of sperm whales, was also sought as a fixative in perfumery. Sperm whaling in the 18th century began with small sloops carrying only a pair of whaleboats (sometimes only one).
Various compounds other than protein are used to enhance the fibre's properties. Pyrrolidine has hygroscopic properties which keeps the silk moist while also warding off ant invasion. It occurs in especially high concentration in glue threads.
|
Stringed instruments can help show the relationship between tension and what in strings?
|
[
"frequencies",
"volumes",
"temperatures",
"lengths"
] |
A
|
f 2 = v w / λ 2 = v w / 2L = 2 f 1 . Similarly, f 3 = 3 f 1 , and so on. All of these frequencies can be changed by adjusting the tension in the string. The greater the tension, the greater v w is and the higher the frequencies. This observation is familiar to anyone who has ever observed a string instrument being tuned. We will see in later chapters that standing waves are crucial to many resonance phenomena, such as in sounding boxes on string instruments.
as a rule two stringed instruments together create a slight 'beat' which does not give a smooth sound." Different music directors may use different numbers of string players and different balances between the sections to create different musical effects. While any combination and number of string instruments is possible in a section, a traditional string section sound is achieved with a violin-heavy balance of instruments.
A string undergoing transverse vibration illustrates many features common to all vibrating acoustic systems, whether these are the vibrations of a guitar string or the standing wave nodes in a studio monitoring room. In this experiment the change in frequency produced when the tension is increased in the string – similar to the change in pitch when a guitar string is tuned – will be measured. From this the mass per unit length of the string / wire can be derived. This is called as the principle of the Melde's Experiment Finding the mass per unit length of a piece of string is also possible by using a simpler method – a ruler and some scales – and this will be used to check the results and offer a comparison.
The mechanism is that the sounding board of the instrument provides a larger surface area to create sound waves than that of the string and therefore acts as a matching element between the acoustic impedance of the string and that of the surrounding air. A larger vibrating surface can sometimes produce better matching; especially at lower frequencies. All lute type instruments traditionally have a bridge, which holds the string at the proper action height from the fret/finger board at one end of the strings.
In music, the term open string refers to the fundamental note of the unstopped, full string. The strings of a guitar are normally tuned to fourths (excepting the G and B strings in standard tuning, which are tuned to a third), as are the strings of the bass guitar and double bass. Violin, viola, and cello strings are tuned to fifths. However, non-standard tunings (called scordatura) exist to change the sound of the instrument or create other playing options.
(equation 28)Thus, for example, all other properties of the string being equal, to make the note one octave higher (2/1) one would need either to decrease its length by half (1/2), to increase the tension to the square (4), or to decrease its mass per length by the inverse square (1/4). These laws are derived from Mersenne's equation 22: f 0 = ν λ = 1 2 L F μ . {\displaystyle f_{0}={\frac {\nu }{\lambda }}={\frac {1}{2L}}{\sqrt {\frac {F}{\mu }}}.} The formula for the fundamental frequency is: f 0 = 1 2 L F μ , {\displaystyle f_{0}={\frac {1}{2L}}{\sqrt {\frac {F}{\mu }}},} where f is the frequency, L is the length, F is the force and μ is the mass per length. Similar laws were not developed for pipes and wind instruments at the same time since Mersenne's laws predate the conception of wind instrument pitch being dependent on longitudinal waves rather than "percussion".
|
Ectotherms undergo a variety of changes at the cellular level to acclimatize to shifts in what?
|
[
"temperature",
"density",
"volume",
"altitude"
] |
A
|
There are 44 autosomes and 2 sex chromosomes in the human genome, for a total of 46 chromosomes (23 pairs). Sex chromosomes specify an organism's genetic sex. Humans can have two different sex chromosomes, one called X and the other Y. Normal females possess two X chromosomes and normal males one X and one Y. An autosome is any chromosome other than a sex chromosome. The Figure below shows a representation of the 24 different human chromosomes. Figure below shows a karyotype of the human genome. A karyotype depicts, usually in a photograph, the chromosomal complement of an individual, including the number of chromosomes and any large chromosomal abnormalities. Karyotypes use chromosomes from the metaphase stage of mitosis.
In order to mimic, it is essential to understand natural properties of ECM and their role in stem cell fate processes. Various studies involving different types of scaffolds that regulate stem cells fate by mimicking these ECM properties have been done.) == References ==
Studies on ectotherms, and other non-mammalian organisms, show that there is no single universal model of telomere erosion; rather, there is wide variation in relevant dynamics across Metazoa, and even within smaller taxonomic groups these patterns appear diverse. Due to the different reproductive timelines of some ectotherms, selection on disease is relevant for a much larger fraction of these creatures’ lives than it is for mammals, so early- and late-life telomere length, and their possible links to cancer, seem especially important in these species from a life history theory point of view. Indeed, ectotherms are more sensitive to environmental variation than endotherms and factors such as temperature are known to their growth and maturation rates, thus, ectothermic telomeres are predicted to be greatly affected by climate change.
Body size is sensitive to changes in temperature due to the thermal dependence of physiological processes. The plankton is mainly composed of ectotherms which are organisms that do not generate sufficient metabolic heat to elevate their body temperature, so their metabolic processes depends on external temperature. Consequently, ectotherms grow more slowly and reach maturity at a larger body size in colder environments, which has long puzzled biologists because classic theories of life-history evolution predict smaller adult sizes in environments delaying growth.
Morphogenesis of animal bodies and change on large and small scales. Niche construction.
Spacing is thought to be essentially random in dicots though mutants do show it is under some form of genetic control, but it is more controlled in monocots, where stomata arise from specific asymmetric divisions of protoderm cells. The smaller of the two cells produced becomes the guard mother cells. Adjacent epidermal cells will also divide asymmetrically to form the subsidiary cells.
|
Convex lenses are thicker in the middle than at the edges so they cause rays of light to converge, or meet, at a point called what?
|
[
"the center",
"the base",
"focus",
"the apex"
] |
C
|
Convex lenses are thicker in the middle than at the edges. They cause rays of light to converge, or meet, at a point called the focus (F). Convex lenses form either real or virtual images. It depends on how close an object is to the lens relative to the focus. Figure below shows how a convex lens works. You can also interact with an animated convex lens at the URL below. An example of a convex lens is a hand lens.
Since the diverging light rays emanating from the lens never come into focus, and those rays are not physically present at the point where they appear to form an image, this is called a virtual image. Unlike real images, a virtual image cannot be projected on a screen, but appears to an observer looking through the lens as if it were a real object at the location of that virtual image. Likewise, it appears to a subsequent lens as if it were an object at that location, so that second lens could again focus that light into a real image, S1 then being measured from the virtual image location behind the first lens to the second lens.
One special application is to determine the focal length of a diverging lens: a light source is placed at twice the focal length of a converging lens on one side and a screen at the same distance on the other side so that the image of the light source is the sharpest possible. When this is achieved, the screen is replaced with a mirror and the diverging lens is inserted between the converging lens and the mirror at such a distance to the mirror that the light returning through the diverging and converging lenses produces a sharp image on top of the luminous object. This is the case when the beam hitting the mirror is collimated.
Like other lenses for vision correction, aspheric lenses can be categorized as convex or concave. Convex aspheric curvatures are used in many presbyopic vari-focal lenses to increase the optical power over part of the lens, aiding in near-pointed tasks such as reading. The reading portion is an aspheric "progressive add". Also, in aphakia or extreme hyperopia, high plus power aspheric lenses can be prescribed, but this practice is becoming obsolete, replaced by surgical implants of intra-ocular lenses.
The greatest radius of curvature of the toric lens surface, R + r, corresponds to the smallest refractive power, S, given by S = n − 1 R + r {\displaystyle S={\frac {n-1}{R+r}}} ,where n is the index of refraction of the lens material. The smallest radius of curvature, r, corresponds to the greatest refractive power, s, given by s = n − 1 r {\displaystyle s={\frac {n-1}{r}}} .Since R + r > r, S < s. The lens behaves approximately like a combination of a spherical lens with optical power s and a cylindrical lens with power s − S. In ophthalmology and optometry, s − S is called the cylinder power of the lens. Note that both the greatest and the smallest curvature have a circular shape. Consequently, in contrast with a popular assumption, the toric lens is not an ellipsoid of revolution.
To protect against "stray light" from the sides, the lenses should fit close enough to the temples and/or merge into broad temple arms or leather blinders. It is not possible to "see" the protection that sunglasses offer. Dark lenses do not automatically filter out more harmful UV radiation and blue light than light lenses.
|
What are magnesium carbonate, aluminum hydroxide, and sodium bicarbonate commonly used as?
|
[
"antacids",
"salts",
"antibiotics",
"antidepressants"
] |
A
|
Magnesium carbonate, aluminum hydroxide, and sodium bicarbonate are commonly used as antacids. Give the empirical formulas and determine the molar masses of these compounds. Based on their formulas, suggest another compound that might be an effective antacid. ♦ Nickel(II) acetate, lead(II) phosphate, zinc nitrate, and beryllium oxide have all been reported to induce cancers in experimental animals.
Sodium sesquicarbonate (systematic name: trisodium hydrogendicarbonate) Na3H(CO3)2 is a double salt of sodium bicarbonate and sodium carbonate (NaHCO3 · Na2CO3), and has a needle-like crystal structure. However, the term is also applied to an equimolar mixture of those two salts, with whatever water of hydration the sodium carbonate includes, supplied as a powder. The dihydrate, Na3H(CO3)2 · 2H2O, occurs in nature as the evaporite mineral trona.Due to concerns about the toxicity of borax which was withdrawn as a cleaning and laundry product, sodium sesquicarbonate is sold in the European Union (EU) as "Borax substitute". It is also known as one of the E number food additives E500(iii).
Hydromagnesite Mg5(CO3)4(OH)2.4H2O Ikaite CaCO3·6(H2O) Lansfordite MgCO3·5(H2O) Monohydrocalcite CaCO3·H2O Natron Na2CO3·10(H2O) Zellerite Ca(UO2)(CO3)2·5(H2O)The carbonate class in both the Dana and the Strunz classification systems include the nitrates.
The sodium carbonate test (not to be confused with sodium carbonate extract test) is used to distinguish between some common metal ions, which are precipitated as their respective carbonates. The test can distinguish between copper (Cu), iron (Fe), and calcium (Ca), zinc (Zn) or lead (Pb). Sodium carbonate solution is added to the salt of the metal. A blue precipitate indicates Cu2+ ion.
Aside from NaOH and KOH, which enjoy very large scale applications, the hydroxides of the other alkali metals also are useful. Lithium hydroxide is a strong base, with a pKb of −0.36. Lithium hydroxide is used in breathing gas purification systems for spacecraft, submarines, and rebreathers to remove carbon dioxide from exhaled gas. 2 LiOH + CO2 → Li2CO3 + H2OThe hydroxide of lithium is preferred to that of sodium because of its lower mass. Sodium hydroxide, potassium hydroxide, and the hydroxides of the other alkali metals are also strong bases.
It is a source of MgO flux in high-temperature glazes (to control melting temperature). It is also employed as a matting agent in earthenware glazes and can be used to produce magnesia mattes at high temperatures. ISO standard for quality (ISO 3262) Patents are pending on the use of magnesium silicate as a cement substitute.
|
What type of taste do bases normally have?
|
[
"sour",
"salty",
"sweet",
"bitter"
] |
D
|
Bases often have a bitter taste and are found in foods less frequently than acids. Many bases, like soaps, are slippery to the touch.
The gustatory system or the sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). A few recognized submodalities exist within taste: sweet, salty, sour, bitter, and umami. Very recent research has suggested that there may also be a sixth taste submodality for fats, or lipids.
It contains two distinct glucophores, as well as two distinct natrophores, within its cyclic structure. Aliphatic alcohols do not contain any gustaphores in their pure state and are considered tasteless. However, many impurities (more than one part per million) have been present in the aliphatic alcohols used in laboratory experiments, resulting in their having been assigned a perceptual "taste."
Cattle have a well-developed sense of taste and can distinguish the four primary tastes (sweet, salty, bitter and sour). They possess around 20,000 taste buds. The strength of taste perception depends on the individual's current food requirements.
The glossopharyngeal nerve connects to taste buds in the posterior two thirds of the tongue. The vagus nerve connects to taste buds in the extreme posterior of the tongue, verging on the pharynx, which are more sensitive to noxious stimuli such as bitterness.Flavor depends on odor, texture, and temperature as well as on taste. Humans receive tastes through sensory organs called taste buds, or gustatory calyculi, concentrated on the upper surface of the tongue.
An organic base is an organic compound which acts as a base. Organic bases are usually, but not always, proton acceptors. They usually contain nitrogen atoms, which can easily be protonated. For example, amines or nitrogen-containing heterocyclic compounds have a lone pair of electrons on the nitrogen atom and can thus act as proton acceptors. Examples include: pyridine alkylamines, such as methylamine imidazole benzimidazole histidine guanidine phosphazene bases hydroxides of quaternary ammonium cations or some other organic cations
|
Which body part helps roundworm prevent their body from expanding?
|
[
"tough cuticle covering",
"scales",
"plate",
"skin"
] |
A
|
Roundworms have a tough covering of cuticle on the surface of their body. It prevents their body from expanding. This allows the buildup of fluid pressure in their partial body cavity. The fluid pressure adds stiffness to the body. This provides a counterforce for the contraction of muscles, allowing roundworms to move easily over surfaces.
Movement and burrowing of earthworms is performed by peristalsis, with the alternation of contraction and relaxation of the circular and longitudinal muscles. To move forward, the anterior portion of the worm is extended forward by the contraction of the circular muscles, while the portion just behind this is made shorter and fatter by the contraction of longitudinal muscles. Next the anterior circular muscles relax, and a wave of circular contraction moves backwards along the worm. At the same time, the cheatae expand to grip the ground as the body shortens and are retracted as it lengthens.
The larvae take up residence in the lymphatic vessels and the lung tissue, hindering respiration and causing chest pain as the disease progresses. This disease can be confused with tuberculosis, asthma, or coughs related to roundworms.The disease itself is a result of a complex interplay between several factors: the worm, the endosymbiotic Wolbachia bacteria within the worm, the host's immune response, and the numerous opportunistic infections and disorders that arise. The adult worms live in the human lymphatic system and obstruct the flow of lymph throughout the body; this results in chronic lymphedema, most often noted in the lower torso (typically in the legs and genitals).
With the help of digestive enzymes from the penetration glands, they penetrate the intestinal mucosa to enter blood and lymphatic vessels. They move along the general circulatory system to various organs, and large numbers are cleared in the liver. The surviving oncospheres preferentially migrate to striated muscles, as well as the brain, liver, and other tissues, where they settle to form cysts — cysticerci.
For example, some tapeworms make some fish behave in such a way that a predatory bird can catch it. The predatory bird is the next host for the parasite in the next stage of its life cycle. Specifically, the tapeworm Schistocephalus solidus turns infected threespine stickleback white, and then makes them more buoyant so that they splash along at the surface of the water, becoming easy to see and easy to catch for a passing bird.Parasites can be internal (endoparasites) or external (ectoparasites).
The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle is found in the walls of the uterus, bladder, intestines, stomach, oesophagus, respiratory airways, and blood vessels. Cardiac muscle is found only in the heart, allowing it to contract and pump blood round the body.
|
The maintenance of constant conditions in the body is also known as what?
|
[
"consciousness",
"homeostasis",
"mononucleosis",
"hypothesis"
] |
B
|
Homeostasis, or the maintenance of constant conditions in the body, is a fundamental property of all living things. In the human body, the substances that participate in chemical reactions must remain within narrows ranges of concentration. Too much or too little of a single substance can disrupt your bodily functions. Because metabolism relies on reactions that are all interconnected, any disruption might affect multiple organs or even organ systems. Water is the most ubiquitous substance in the chemical reactions of life. The interactions of various aqueous solutions—solutions in which water is the solvent—are continuously monitored and adjusted by a large suite of interconnected feedback systems in your body. Understanding the ways in which the body maintains these critical balances is key to understanding good health.
Chronic fatigue syndrome is a name for a group of diseases that are dominated by persistent fatigue. The fatigue is not due to exercise and is not relieved by rest.Through numerous studies, it has been shown that people with chronic fatigue syndrome have an integral central fatigue component. In one study, the subjects' skeletal muscles were checked to ensure they had no defects that prevented their total use. It was found that the muscles functioned normally on a local level, but they failed to function to their full extent as a whole.
To achieve this, the body alters three main things to achieve a constant, normal body temperature: Heat transfer to the epidermis The rate of evaporation The rate of heat productionThe hypothalamus plays an important role in thermoregulation. It connects to thermal receptors in the dermis, and detects changes in surrounding blood to make decisions of whether to stimulate internal heat production or to stimulate evaporation. There are two main types of stresses that can be experienced due to extreme environmental temperatures: heat stress and cold stress. Heat stress is physiologically combated in four ways: radiation, conduction, convection, and evaporation.
The human skeletal system is a complex organ in constant equilibrium with the rest of the body. In addition to support and structure of the body, bone is the major reservoir for many minerals and compounds essential for maintaining a healthy pH balance. The deterioration of the body with age renders the elderly particularly susceptible to and affected by poor bone health. Illnesses like osteoporosis, characterized by weakening of the bone's structural matrix, increases the risk of hip-fractures and other life-changing secondary symptoms.
It must also maintain the correct body temperature, an acceptable pressure on the body and deal with the body's waste products. Shielding against harmful external influences such as radiation and micro-meteorites may also be necessary. Components of the life-support system are life-critical, and are designed and constructed using safety engineering techniques.
Being able to regulate fatigue in terms of information about the benefits and costs of continued exercise would enhance biological fitness. Low level theories exist that suggest that fatigue is due mechanical failure of the exercising muscles ("peripheral fatigue").
|
What is the term for tough protein fibers that connects bones to each other?
|
[
"ligaments",
"tetons",
"cords",
"muscles"
] |
A
|
Ligaments are made of tough protein fibers and connect bones to each other. Your bones, cartilage, and ligaments make up your skeletal system .
The extracellular matrix of bone is laid down by osteoblasts, which secrete both collagen and ground substance. These synthesise collagen within the cell and then secrete collagen fibrils. The collagen fibers rapidly polymerise to form collagen strands. At this stage, they are not yet mineralised, and are called "osteoid".
Bone is a form of connective tissue found in the body, composed largely of hardened hydroxyapatite-containing collagen. In larger mammals, it is arranged in osteon regions. Bone matrix allows mineral salts such as calcium to be stored and provides protection for internal organs and support for locomotion.
The hollow tubular structure of bones provide considerable resistance against compression while staying lightweight. Most cells in bones are either osteoblasts, osteoclasts, or osteocytes.Bone tissue is a type of dense connective tissue. One of the types of tissue that makes up bone tissue is mineralized tissue and this gives it rigidity and a honeycomb-like three-dimensional internal structure.
For example, using AFM–based nanoindentation it has been shown that a single collagen fibril is a heterogeneous material along its axial direction with significantly different mechanical properties in its gap and overlap regions, correlating with its different molecular organizations in these two regions.Collagen fibrils/aggregates are arranged in different combinations and concentrations in various tissues to provide varying tissue properties. In bone, entire collagen triple helices lie in a parallel, staggered array. 40 nm gaps between the ends of the tropocollagen subunits (approximately equal to the gap region) probably serve as nucleation sites for the deposition of long, hard, fine crystals of the mineral component, which is hydroxylapatite (approximately) Ca10(OH)2(PO4)6. Type I collagen gives bone its tensile strength.
life cycle ligament The fibrous connective tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament. light-independent reactions See Calvin cycle.
|
What is the study of macroscopic properties, atomic properties, and phenomena in chemical systems?
|
[
"differential chemistry",
"thermal chemistry",
"molecular chemistry",
"physical chemistry"
] |
D
|
Physical chemistry is the study of macroscopic properties, atomic properties, and phenomena in chemical systems. A physical chemist may study such things as the rates of chemical reactions, the energy transfers that occur in reactions, or the physical structure of materials at the molecular level.
Constituting the scientific study of matter at the atomic and molecular scale, chemistry deals primarily with collections of atoms, such as gases, molecules, crystals, and metals. The composition, statistical properties, transformations, and reactions of these materials are studied. Chemistry also involves understanding the properties and interactions of individual atoms and molecules for use in larger-scale applications.
Its most important experimental techniques are the various types of spectroscopy; scattering is also used. The field is closely related to atomic physics and overlaps greatly with theoretical chemistry, physical chemistry and chemical physics.
Physical chemistry: free energy, phase diagram, phase rule, transport phenomena Statistical mechanics: statistical ensemble, phase space, chemical potential, Gibbs entropy, Gibbs paradox Mathematics: Vector Analysis, convex analysis, Gibbs phenomenon Electromagnetism: Maxwell's equations, birefringence
A system is composed of particles, whose average motions define its properties, and those properties are in turn related to one another through equations of state. Properties can be combined to express internal energy and thermodynamic potentials, which are useful for determining conditions for equilibrium and spontaneous processes. With these tools, thermodynamics can be used to describe how systems respond to changes in their environment.
Photochemistry – study of chemical reactions that proceed with the absorption of light by atoms or molecules. Quantum chemistry – branch of chemistry whose primary focus is the application of quantum mechanics in physical models and experiments of chemical systems. Solid-state chemistry – study of the synthesis, structure, and properties of solid phase materials, particularly, but not necessarily exclusively of, non-molecular solids.
|
Bones, cartilage, and ligaments make up what anatomical system?
|
[
"Integumentary system",
"Lymphatic system",
"skeletal system",
"Muscular system"
] |
C
|
The skeletal system is made up of bones, cartilage, and ligaments. The skeletal system has many important functions in your body. What bones protect the heart and lungs? What protects the brain?.
A true endoskeleton is derived from mesodermal tissue. Such a skeleton is present in echinoderms and chordates. The poriferan "skeleton" consists of microscopic calcareous or siliceous spicules or a spongin network.
The dorsal ligaments are strong, flat bands. The first metatarsal is joined to the first cuneiform by a broad, thin band; the second has three, one from each cuneiform bone; the third has one from the third cuneiform; the fourth has one from the third cuneiform and one from the cuboid; and the fifth, one from the cuboid.
Modern fish are either cartilaginous or bony. Cartilaginous fishes have skeletons made of cartilage while bony fishes have skeletons made of bone. Because rays and sharks are closely related, they are often studied together.
The skeletal portion of the system serves as the main storage system for calcium and phosphorus and contains critical components of the hematopoietic system.This system describes how bones are connected to other bones and muscle fibers via connective tissue such as tendons and ligaments. The bones provide stability to the body. Muscles keep bones in place and also play a role in the movement of bones.
This is followed by definition of specific cellular subtypes (meniscal progenitors, articular progenitors, synovial progenitors, and ligament progenitors) that will eventually form the joint capsule. Finally, the joint capsule matures and forms a cavity, with a central meniscus, and an encasement of synovium. This final structure will form several distinct layers of the articular cartilage found in all synovial joints including the Deep Zone (closest to the bone), Middle Zone, and Superficial Zone (closest to the synovial fluid).
|
What is the first part of the large intestine called?
|
[
"cecum",
"duodenum",
"colon",
"jejunum"
] |
A
|
Cecum The first part of the large intestine is the cecum, a sac-like structure that is suspended inferior to the ileocecal valve. It is about 6 cm (2.4 in) long, receives the contents of the ileum, and continues the absorption of water and salts. The appendix (or vermiform appendix) is a winding tube that attaches to the cecum. Although the 7.6-cm (3-in) long appendix contains lymphoid tissue, suggesting an immunologic function, this organ is generally considered vestigial. However, at least one recent report postulates a survival advantage conferred by the appendix: In diarrheal illness, the appendix may serve as a bacterial reservoir to repopulate the enteric bacteria for those surviving the initial phases of the illness. Moreover, its twisted anatomy provides a haven for the accumulation and multiplication of enteric bacteria. The mesoappendix, the mesentery of the appendix, tethers it to the mesentery of the ileum.
The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine may be used instead of duodenum. In mammals the duodenum may be the principal site for iron absorption.In humans, the duodenum is a C-shaped hollow jointed tube, 25–38 centimetres (10–15 inches) in length, lying adjacent to the stomach (and connecting it to the small intestine).
In the stomach, the epithelium is simple columnar, and is organised into gastric pits and glands to deal with secretion. In the small intestine, epithelium is simple columnar and specialised for absorption. It is organised into plicae circulares and villi, and the enterocytes have microvilli.
This starts at the mouth and ends at the anus, covering a distance of about nine metres.A major digestive organ is the stomach. Within its mucosa are millions of embedded gastric glands. Their secretions are vital to the functioning of the organ.
In these sections of the gut there is clear boundary between the gut and the surrounding tissue. These parts of the tract have a mesentery. Regions of the gastrointestinal tract behind the peritoneum (called retroperitoneal) are covered with adventitia. They blend into the surrounding tissue and are fixed in position (for example, the retroperitoneal section of the duodenum usually passes through the transpyloric plane). The retroperitoneal regions include the oral cavity, esophagus, pylorus of the stomach, distal duodenum, ascending colon, descending colon and anal canal.
The greater omentum is the larger of the two peritoneal folds. It consists of a double sheet of peritoneum, folded on itself so that it has four layers.The two layers of the greater omentum descend from the greater curvature of the stomach and the beginning of the duodenum. They pass in front of the small intestines, sometimes as low as the pelvis, before turning on themselves, and ascending as far as the transverse colon, where they separate and enclose that part of the intestine.These individual layers are easily seen in the young, but in the adult they are more or less inseparably blended. The left border of the greater omentum is continuous with the gastrosplenic ligament; its right border extends as far as the beginning of the duodenum.
|
What occurs when nature reclaims areas formerly occupied by life?
|
[
"secondary succession",
"typical succession",
"tertiary succession",
"primary succession"
] |
A
|
Forest and Kim Starr (Flickr:Starr Environmental). Secondary succession occurs when nature reclaims areas formerly occupied by life . CC BY 2.0.
A remnant natural area, also known as remnant habitat, is an ecological community containing native flora and fauna that has not been significantly disturbed by destructive activities such as agriculture, logging, pollution, development, fire suppression, or non-native species invasion. The more disturbed an area has been, the less characteristic it becomes of remnant habitat. Remnant areas are also described as "biologically intact" or "ecologically intact. "Remnant natural areas are often used as reference ecosystems in ecological restoration projects.
Often, this combination only occurs in sites which are thoroughly flooded once every few years, which brings in fresh sand and clears away vegetation. As human coastal management strategies worked to minimize unpredictable flooding, their old habitats often became overgrown, and their populations declined.
: 43 Ecosystems can also be divided and degraded by infrastructure development outside of urban areas. : 46 Biodiversity loss can sometimes be reversed through ecological restoration or ecological resilience, such as through the restoration of abandoned agricultural areas;: 45 however, it may also be permanent (e.g. through land loss). The planet's ecosystem is quite sensitive: occasionally, minor changes from a healthy equilibrium can have dramatic influence on a food web or food chain, up to and including the coextinction of that entire food chain.
Land restoration can include the process of cleaning up and rehabilitating a site that has sustained environmental degradation, such as those by natural cause (desertification) and those caused by human activity (strip mining), to restore that area back to its natural state as a wildlife home and balanced habitat.
Land degradation is "the reduction or loss of the biological or economic productivity and complexity" of land as a result of human activity. : 42 Land degradation is driven by many different activities, including agriculture, urbanization, energy production, and mining. : 43 Humans have altered more than three-quarters of ice-free land through habitation and other use, fundamentally changing ecosystems.
|
To solubilize the fats so that they can be absorbed, what organ secretes a fluid called bile into the small intestine?
|
[
"small intestine",
"gall bladder",
"stomach",
"spleen"
] |
B
|
A related mechanism allows us to absorb and digest the fats in buttered popcorn and French fries. To solubilize the fats so that they can be absorbed, the gall bladder secretes a fluid called bile into the small intestine. Bile contains a variety of bile salts, detergent-like molecules that emulsify the fats.
The presence of biliary acids in the intestines helps in absorption of fats and other substances.
After being transported to the liver by HDL, cholesterol is delivered to the intestines via bile production. However, 92-97% is reabsorbed in the intestines and recycled via enterohepatic circulation.
The muscular layer of the body is of smooth muscle tissue that helps the gallbladder contract, so that it can discharge its bile into the bile duct. The gallbladder needs to store bile in a natural, semi-liquid form at all times. Hydrogen ions secreted from the inner lining of the gallbladder keep the bile acidic enough to prevent hardening.
The cells that do this are arranged in clusters called acini. Secretions into the middle of the acinus accumulate in intralobular ducts, which drain to the main pancreatic duct, which drains directly into the duodenum. About 1.5 - 3 liters of fluid are secreted in this manner every day.The cells in each acinus are filled with granules containing the digestive enzymes.
To dilute the bile, water and electrolytes from the digestion system are added. Also, salts attach themselves to cholesterol molecules in the bile to keep them from crystallising. If there is too much cholesterol or bilirubin in the bile, or if the gallbladder does not empty properly the systems can fail.
|
When the hemoglobin loses its oxygen, it changes to what color?
|
[
"purple red",
"bluish red",
"grayish red",
"light pink"
] |
B
|
The structure of heme (Figure 19.29), the iron-containing complex in hemoglobin, is very similar to that in chlorophyll. In hemoglobin, the red heme complex is bonded to a large protein molecule (globin) by the attachment of the protein to the heme ligand. Oxygen molecules are transported by hemoglobin in the blood by being bound to the iron center. When the hemoglobin loses its oxygen, the color changes to a bluish red. Hemoglobin will only transport oxygen if the iron is Fe2+; oxidation of the iron to Fe3+ prevents oxygen transport.
Some oxyhemoglobin loses oxygen and becomes deoxyhemoglobin. Deoxyhemoglobin binds most of the hydrogen ions as it has a much greater affinity for more hydrogen than does oxyhemoglobin.
(Additionally, this hydrogen bonding results in the tilting of the oxygen molecule, resulting in a Fe–O–O bond angle of around 120° that avoids the formation of Fe–O–Fe or Fe–O2–Fe bridges that would lead to electron transfer, the oxidation of Fe2+ to Fe3+, and the destruction of hemoglobin.) This results in a movement of all the protein chains that leads to the other subunits of hemoglobin changing shape to a form with larger oxygen affinity. Thus, when deoxyhemoglobin takes up oxygen, its affinity for more oxygen increases, and vice versa.
Changes in light intensity can be related to changes in relative concentrations of hemoglobin through the modified Beer–Lambert law (mBLL). The Beer lambert-law has to deal with concentration of hemoglobin. This technique also measures relative changes in light attenuation as well as using mBLL to quantify hemoglobin concentration changes.
To provide a simplified synopsis of the molecular mechanism of systemic gas exchange in layman's terms, upon inhalation of air it was widely thought oxygen binding to any of the heme sites triggers a conformational change in the globin/protein unit of hemoglobin which then enables the binding of additional oxygen to each of the other vacant heme sites. Upon arrival to the cell/tissues, oxygen release into the tissue is driven by "acidification" of the local pH (meaning a relatively higher concentration of 'acidic' protons/hydrogen ions) caused by an increase in the biotransformation of carbon dioxide waste into carbonic acid via carbonic anhydrase. In other words, oxygenated arterial blood arrives at cells in the "hemoglobin R-state" which has deprotonated/unionized amino acid residues (regarding nitrogen/amines) due to the less-acidic arterial pH environment (arterial blood averages pH 7.407 whereas venous blood is slightly more acidic at pH 7.371).
Bilirubin (BR) (from the Latin for "red bile") is a red-orange compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from the destruction of aged or abnormal red blood cells. In the first step of bilirubin synthesis, the heme molecule is stripped from the hemoglobin molecule. Heme then passes through various processes of porphyrin catabolism, which varies according to the region of the body in which the breakdown occurs.
|
How are weather patterns formed?
|
[
"uneven heating of the atmosphere",
"carbon dioxide",
"pollution from planes",
"the moon's gravitational pull"
] |
A
|
Weather refers to conditions of the atmosphere at a given time and place. It occurs because of unequal heating of the atmosphere. Humidity, clouds, and precipitation are important weather factors.
Banding appears because the protective boundary layer created by the wind-most trees is eventually disrupted by turbulence, exposing more distant downwind trees to freezing damage once again. When there is no directional resource flow across the landscape, spatial patterns may still appear in various regular and irregular forms along the rainfall gradient, including, in particular, hexagonal gap patterns at relatively high rainfall rates, stripe patterns at intermediate rates, and hexagonal spot patterns at low rates. The presence of a clear directionality to some important factor (such as a freezing wind or surface flow down a slope) favors the formation of stripes (bands), oriented perpendicular to the flow direction, in wider ranges of rainfall rates. Several mathematical models have been published that reproduce a wide variety of patterned landscapes, including: semi-arid “tiger bush”, hexagonal “fairy-circle” gap patterns, woody-herbaceous landscapes, salt marshes, fog dependent desert vegetation, mires and fens. Although not strictly vegetation, sessile marine invertebrates such as mussels and oysters, have also been shown to form banding patterns.
The leading area of a squall line is composed primarily of multiple updrafts, or singular regions of an updraft, rising from ground level to the highest extensions of the troposphere, condensing water and building a dark, ominous cloud to one with a noticeable overshooting top and anvil (thanks to synoptic scale winds). Because of the chaotic nature of updrafts and downdrafts, pressure perturbations are important. Precipitation cooled air from downdrafts usually outwardly just above the surface and lifts air into the updrafts unless gushing too far out and cutting off this inflow. Visually this process may take the form of a shelf cloud, often with a turbulent appearance.
This means that matter is exchanged across the air-reaction mixture interface, due to the fluctuations in the molecular nature of chemical systems. The temperature can affect the formation of pattern. Colder temperature formed a clearer pattern than hot temperature.
The formation of a downburst starts with hail or large raindrops falling through drier air. Hailstones melt and raindrops evaporate, pulling latent heat from surrounding air and cooling it considerably. Cooler air has a higher density than the warmer air around it, so it sinks to the surface. As the cold air hits the ground or water it spreads out and a mesoscale front can be observed as a gust front.
Mechanisms of producing precipitation include convective, stratiform, and orographic rainfall. Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation, while stratiform processes involve weaker upward motions and less intense precipitation over a longer duration. Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice. Droughts occur mainly in areas where normal levels of rainfall are, in themselves, low.
|
Boyle discovered that what property of a gas is inversely proportional to its volume?
|
[
"temperature",
"amount",
"pressure",
"mass"
] |
C
|
in a one-liter container (Figure 22.15). In this case, the force exerted by the movement of the gas molecules against the walls of the two-liter container is lower than the force exerted by the gas molecules in the one-liter container. Therefore, the pressure is lower in the two-liter container and higher in the one-liter container. At a constant temperature, changing the volume occupied by the gas changes the pressure, as does changing the number of gas molecules. Boyle’s law describes the relationship between volume and pressure in a gas at a constant temperature. Boyle discovered that the pressure of a gas is inversely proportional to its volume: If volume increases, pressure decreases. Likewise, if volume decreases, pressure increases. Pressure and volume are inversely related (P = k/V). Therefore, the pressure in the one-liter container (one-half the volume of the two-liter container) would be twice the pressure in the two-liter container. Boyle’s law is expressed by the following formula:.
Experiments on the properties of gases started early in the seventeenth century. By the middle of the seventeenth century Robert Boyle had derived the inverse relationship between the pressure and the volume of gases. About the same time, Guillaume Amontons started looking into temperature effects on gas. Various gas experiments continued for the next 200 years.
Gas equations of state, which may be expressed in combination as the Combined gas law, or the Ideal gas law within the range of pressures normally encountered by divers, or as the traditionally expressed gas laws relating the relationships between two properties when the others are held constant, are used to calculate variations of pressure, volume and temperature, such as: Boyle's law, which describes the change in volume with a change in pressure at a constant temperature. For example, the volume of gas in a non-rigid container (such as a diver's lungs or buoyancy compensation device), decreases as external pressure increases while the diver descends in the water. Likewise, the volume of gas in such non-rigid containers increases on the ascent. Changes in the volume of gases in the diver and the diver's equipment affect buoyancy.
This law has the following important consequences: If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas. If the temperature and volume remain constant, then the pressure of the gas changes is directly proportional to the number of molecules of gas present. If the number of gas molecules and the temperature remain constant, then the pressure is inversely proportional to the volume. If the temperature changes and the number of gas molecules are kept constant, then either pressure or volume (or both) will change in direct proportion to the temperature.
The laws describing the behaviour of gases under fixed pressure, volume and absolute temperature conditions are called Gas Laws. The basic gas laws were discovered by the end of the 18th century when scientists found out that relationships between pressure, volume and temperature of a sample of gas could be obtained which would hold to approximation for all gases. These macroscopic gas laws were found to be consistent with atomic and kinetic theory.
In physical chemistry, Henry's law is a gas law that states that the amount of dissolved gas in a liquid is directly proportional to its partial pressure above the liquid. The proportionality factor is called Henry's law constant. It was formulated by the English chemist William Henry, who studied the topic in the early 19th century.
|
What amazing machines smash particles that are smaller than atoms into each other head-on?
|
[
"nitrogen accelerators",
"particle accelerators",
"observant accelerators",
"absorption accelerators"
] |
B
|
Scientists have built machines called particle accelerators. These amazing tools smash particles that are smaller than atoms into each other head-on. This creates new particles. Scientists use particle accelerators to learn about nuclear fusion in stars. They can also learn about how atoms came together in the early universe. Two well-known accelerators are SLAC, in California, and CERN, in Switzerland.
An example is the cream separator found in dairies. Very high speed centrifuges and ultracentrifuges able to provide very high accelerations can separate fine particles down to the nano-scale, and molecules of different masses. Large centrifuges are used to simulate high gravity or acceleration environments (for example, high-G training for test pilots). Medium-sized centrifuges are used in washing machines and at some swimming pools to draw water out of fabrics. Gas centrifuges are used for isotope separation, such as to enrich nuclear fuel for fissile isotopes.
By the late 1970s and early 1980s a generation of accelerators had been made obsolete by newer machines in terms of being useful for leading edge research. Still useful for other tasks, these older machines were turned to a wide variety of new studies. One particularly active area of research is collisions between higher mass particles, instead of fundamental particles like electrons or protons.
According to Richard Feynman, it was his former graduate student and collaborator Albert Hibbs who originally suggested to him (circa 1959) the idea of a medical use for Feynman's theoretical micro-machines (see biological machine). Hibbs suggested that certain repair machines might one day be reduced in size to the point that it would, in theory, be possible to (as Feynman put it) "swallow the surgeon". The idea was incorporated into Feynman's case study 1959 essay There's Plenty of Room at the Bottom.Since nano-robots would be microscopic in size, it would probably be necessary for very large numbers of them to work together to perform microscopic and macroscopic tasks. These nano-robot swarms, both those unable to replicate (as in utility fog) and those able to replicate unconstrained in the natural environment (as in grey goo and synthetic biology), are found in many science fiction stories, such as the Borg nano-probes in Star Trek and The Outer Limits episode "The New Breed".
A high speed impact leads to destruction of particles into pieces of different size. Big particles (greater than 1 mm) fall down to outlet (5) and later they transport to hopper by an elevator. Other particles (less than 1 mm) lift by air stream into a classifier where blades (4) make rotating dust flow.
During high-energy milling the powder particles are repeatedly flattened, cold welded, fractured and rewelded. Whenever two steel balls collide, some powder is trapped between them. Typically, around 1000 particles with an aggregate weight of about 0.2 mg are trapped during each collision. The force of the impact plastically deforms the powder particles, leading to work hardening and fracture.
|
The interaction of what opposite factors describe a biome and ecosystem?
|
[
"metastasis and biotic",
"innate and biotic",
"abiotic and biotic",
"hygroscopic and abiotic"
] |
C
|
The abiotic factors, such as the amount of rainfall and the temperature, are going to influence other abiotic factors, such as the quality of the soil. This, in turn, is going to influence the plants that migrate into the ecosystem and thrive in that biome. Recall that migration is the movement of an organism into or out of a population. It can also refer to a whole new species moving into a habitat . The type of plants that live in a biome are going to attract a certain type of animal to that habitat. It is the interaction of the abiotic and biotic factors that describe a biome and ecosystem. In aquatic biomes, abiotic factors such as salt, sunlight and temperature play significant roles.
Ecology (from Greek: οἶκος, "house", or "environment"; -λογία, "study of") is a branch of biology concerning interactions among organisms and their biophysical environment, which includes both biotic and abiotic components. Topics of interest include the biodiversity, distribution, biomass, and populations of organisms, as well as cooperation and competition within and between species. Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, pedogenesis, nutrient cycling, and niche construction, regulate the flux of energy and matter through an environment. These processes are sustained by organisms with specific life history traits.
Frid adds, "Fish communities can be altered in a number of ways, for example they can decrease if particular sized individuals of a species are targeted, as this affects predator and prey dynamics. Fishing, however, is not the sole perpetrator of changes to marine life – pollution is another example No one factor operates in isolation and components of the ecosystem respond differently to each individual factor. "In contrast to the traditional approach of focusing on a single species, the ecosystem-based approach is organized in terms of ecosystem services.
Whatever name is applied, it deals with the ways in which plants respond to their environment and so overlaps with the field of ecology. Environmental physiologists examine plant response to physical factors such as radiation (including light and ultraviolet radiation), temperature, fire, and wind.
The scale of ecological dynamics can operate like a closed system, such as aphids migrating on a single tree, while at the same time remaining open with regard to broader scale influences, such as atmosphere or climate. Hence, ecologists classify ecosystems hierarchically by analyzing data collected from finer scale units, such as vegetation associations, climate, and soil types, and integrate this information to identify emergent patterns of uniform organization and processes that operate on local to regional, landscape, and chronological scales. To structure the study of ecology into a conceptually manageable framework, the biological world is organized into a nested hierarchy, ranging in scale from genes, to cells, to tissues, to organs, to organisms, to species, to populations, to communities, to ecosystems, to biomes, and up to the level of the biosphere. This framework forms a panarchy and exhibits non-linear behaviors; this means that "effect and cause are disproportionate, so that small changes to critical variables, such as the number of nitrogen fixers, can lead to disproportionate, perhaps irreversible, changes in the system properties. ": 14
In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or of different species (interspecific interactions). These effects may be short-term, or long-term, both often strongly influence the adaptation and evolution of the species involved. Biological interactions range from mutualism, beneficial to both partners, to competition, harmful to both partners.
|
What is caused by differences in density at the top and bottom of the ocean?
|
[
"deep currents",
"shallow currents",
"still water",
"flat currents"
] |
A
|
Currents also flow deep below the surface of the ocean. Deep currents are caused by differences in density at the top and bottom. More dense water takes up less space than less dense water. It has the same mass but less volume. Water that is more dense sinks. Less dense water rises. What can make water more dense?.
For the Charney bottom type this is similar, but now the westward flow in the deeper ocean is found to be stronger. The Charney surface and Phillips types exist for weaker background flows, also explaining why these are dominant in the ocean gyres. == References ==
In addition, the build-up of water at this region leads to a slight increase in sea level. This increases the pressure on the water column, and results in downwelling. In some cases, this can support local marine communities as organisms, such as sargassum, that float in the upper ocean layers will move towards the front with the water and remain in the upper layers close to the front. Examples of subtropical convergence fronts can be found in among others the Sargasso Sea and North Pacific Ocean, but also in the southern parts of the Atlantic, Indian, and Pacific Oceans.
Phillips, O. M. (1977). The dynamics of the upper ocean (2nd ed.).
The particles in the layer may come from the upper ocean layers and from stripping the sediments from the ocean floor by currents. Its thickness depends on bottom current velocity and is a result of balance between gravitational settling of particles and turbulence of the current. The formation mechanisms of nepheloid layers may vary, but primarily depend on deep ocean convection. Nepheloid layers can impact the accuracy of instruments when measuring bathymetry as well as affect the types of marine life in an area. There are several significant examples of nepheloid layers across the globe, including within the Gulf of Mexico and the Porcupine Bank.
Tide – Rise and fall of the sea level under astronomical gravitational influences – processes due to tidal currents, creates tidal flats (fine-grained, ripple marks, cross-beds). Common sediments are silt and clay Lagoonal – Shallow body of water separated from a larger one by a narrow landform. Little transportation, creates lagoon bottom environment.
|
What is the layer of tissue between the body and shell called?
|
[
"collagen",
"cuticle",
"epidermis",
"mantle"
] |
D
|
Mollusks have a hard outer shell. There is a layer of tissue called the mantle between the shell and the body.
The body of the polyp may be roughly compared in a structure to a sac, the wall of which is composed of two layers of cells. The outer layer is known technically as the ectoderm, the inner layer as the endoderm (or gastroderm). Between ectoderm and endoderm is a supporting layer of structureless gelatinous substance termed mesoglea, secreted by the cell layers of the body wall. The mesoglea can be thinner than the endoderm or ectoderm or comprise the bulk of the body as in larger jellyfish.
The dermis is the underlying connective tissue layer that supports the epidermis. It is composed of dense irregular connective tissue and areolar connective tissue such as a collagen with elastin arranged in a diffusely bundled and woven pattern. The dermis has two layers: the papillary dermis and the reticular layer. The papillary layer is the superficial layer that forms finger-like projections into the epidermis (dermal papillae), and consists of highly vascularized, loose connective tissue.
In zoology, the epidermis is an epithelium (sheet of cells) that covers the body of a eumetazoan (animal more complex than a sponge). Eumetazoa have a cavity lined with a similar epithelium, the gastrodermis, which forms a boundary with the epidermis at the mouth.Sponges have no epithelium, and therefore no epidermis or gastrodermis. The epidermis of a more complex invertebrate is just one layer deep, and may be protected by a non-cellular cuticle. The epidermis of a higher vertebrate has many layers, and the outer layers are reinforced with keratin and then die. == References ==
The subcutaneous tissue of penis (or superficial penile fascia) is continuous above with the fascia of Scarpa, and below with the dartos tunic of the scrotum and the fascia of Colles. It is sometimes just called the "dartos layer".It attaches at the intersection of the body and glans.The term "superficial penile fascia" is more common, but "subcutaneous tissue of penis" is the term used by Terminologia Anatomica.
Like those of cnidarians, (jellyfish, sea anemones, etc.), ctenophores' bodies consist of a relatively thick, jelly-like mesoglea sandwiched between two epithelia, layers of cells bound by inter-cell connections and by a fibrous basement membrane that they secrete. The epithelia of ctenophores have two layers of cells rather than one, and some of the cells in the upper layer have several cilia per cell.The outer layer of the epidermis (outer skin) consists of: sensory cells; cells that secrete mucus, which protects the body; and interstitial cells, which can transform into other types of cell. In specialized parts of the body, the outer layer also contains colloblasts, found along the surface of tentacles and used in capturing prey, or cells bearing multiple large cilia, for locomotion. The inner layer of the epidermis contains a nerve net, and myoepithelial cells that act as muscles.The internal cavity forms: a mouth that can usually be closed by muscles; a pharynx ("throat"); a wider area in the center that acts as a stomach; and a system of internal canals.
|
Well suited to absorb water and dissolved minerals from the soil, thin-walled dermal cells and tiny hairs cover what basic plant structures?
|
[
"leaves",
"roots",
"flowers",
"stems"
] |
B
|
Roots are covered with thin-walled dermal cells and tiny root hairs. These features are well suited to absorb water and dissolved minerals from the soil.
Root hair cells improve plant water absorption by increasing root surface area to volume ratio which allows the root hair cell to take in more water. The large vacuole inside root hair cells makes this intake much more efficient. Root hairs are also important for nutrient uptake as they are main interface between plants and mycorrhizal fungi.
Good soil requires sufficient water and nutrient loading as well as little compaction to allow easy exchange of gases. The roots of plants require continuous transportation of carbon dioxide and oxygen to and from the surface. Pumice improves the quality of soil because of its porous properties; water and gases can be transported easily through the pores and nutrients can be stored in the microscopic holes.
These are typically more elongated in the leaves of monocots than in those of dicots. Trichomes or hairs grow out from the epidermis in many species. In the root epidermis, epidermal hairs termed root hairs are common and are specialized for the absorption of water and mineral nutrients. In plants with secondary growth, the epidermis of roots and stems is usually replaced by a periderm through the action of a cork cambium.
Acid, alkaline Some specialised angiosperms are able to flourish in extremely acid or alkaline habitats. The sundews, many of which live in nutrient-poor acid bogs, are carnivorous plants, able to derive nutrients such as nitrate from the bodies of trapped insects. Other flowers such as Gentiana verna, the spring gentian, are adapted to the alkaline conditions found on calcium-rich chalk and limestone, which give rise to often dry topographies such as limestone pavement. Herbaceous, woody, climbing As for their growth habit, the flowering plants range from small, soft herbaceous plants, often living as annuals or biennials that set seed and die after one growing season, to large perennial woody trees that may live for many centuries and grow to many metres in height. Some species grow tall without being self-supporting like trees by climbing on other plants in the manner of vines or lianas.
These plants grow best in wet, poorly drained areas with nutrient rich soil. They grow well in nitrogen rich soil, and are able to tolerate high levels of heavy metals, such as arsenic, cadmium, and lead.
|
What is the major artery of the body, taking oxygenated blood to the organs and muscles of the body?
|
[
"carotid",
"capillary",
"aorta",
"diastolic"
] |
C
|
The Heart The heart is a complex muscle that consists of two pumps: one that pumps blood through pulmonary circulation to the lungs, and the other that pumps blood through systemic circulation to the rest of the body’s tissues (and the heart itself). The heart is asymmetrical, with the left side being larger than the right side, correlating with the different sizes of the pulmonary and systemic circuits (Figure 16.10). In humans, the heart is about the size of a clenched fist; it is divided into four chambers: two atria and two ventricles. There is one atrium and one ventricle on the right side and one atrium and one ventricle on the left side. The right atrium receives deoxygenated blood from the systemic circulation through the major veins: the superior vena cava, which drains blood from the head and from the veins that come from the arms, as well as the inferior vena cava, which drains blood from the veins that come from the lower organs and the legs. This deoxygenated blood then passes to the right ventricle through the tricuspid valve, which prevents the backflow of blood. After it is filled, the right ventricle contracts, pumping the blood to the lungs for reoxygenation. The left atrium receives the oxygen-rich blood from the lungs. This blood passes through the bicuspid valve to the left ventricle where the blood is pumped into the aorta. The aorta is the major artery of the body, taking oxygenated blood to the organs and muscles of the body. This pattern of pumping is referred to as double circulation and is found in all mammals. (Figure 16.10).
The deep femoral artery is the main supply of oxygenated blood to the thigh.The medial circumflex femoral artery is distributes to the adductor group (adductor longus, magnus, and brevis), gracilis, and pectineus. It also supplies the femoral head and neck.The lateral circumflex femoral artery supplies muscles of the knee extensor group (vastus lateralis, vastus intermedius, and rectus femoris).The perforating arteries supply the hamstring muscles (semitendinosus, semimembranosus, and biceps femoris).
Seven arteries conduct blood from the heart to various regions of the body. Each artery branches extensively, and smaller arteries ultimately end in the hemocoel. Venous blood drains into the sternal sinus, where it is conveyed by channels to the gills for aeration and returned again to the pericardial sinus.
Systemic arteries can be subdivided into two types—muscular and elastic—according to the relative compositions of elastic and muscle tissue in their tunica media as well as their size and the makeup of the internal and external elastic lamina. The larger arteries (>10 mm diameter) are generally elastic and the smaller ones (0.1–10 mm) tend to be muscular. Systemic arteries deliver blood to the arterioles, and then to the capillaries, where nutrients and gases are exchanged. After traveling from the aorta, blood travels through peripheral arteries into smaller arteries called arterioles, and eventually to capillaries. Arterioles help in regulating blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the capillaries.
The movement of the eye is controlled by six distinct extraocular muscles, a superior, an inferior, a medial and a lateral rectus, as well as a superior and an inferior oblique. The superior ophthalmic vein is a sigmoidal vessel along the superior margin of the orbital canal that drains deoxygenated blood from surrounding musculature. The ophthalmic artery is a crucial structure in the orbit, as it is often the only source of collateral blood to the brain in cases of large internal carotid infarcts, as it is a collateral pathway to the circle of Willis.
Blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from the tissues.
|
What do you call a growing mass of cancerous cells that pushes into nearby tissues?
|
[
"bacteria",
"pallet",
"calcium",
"tumor"
] |
D
|
Lung cancer is a disease in which the cells found in the lungs grow out of control. The growing mass of cells can form a tumor that pushes into nearby tissues. The tumor will affect how these tissues work. Lung cancer is the most common cause of cancer-related death in men, and the second most common in women. It is responsible for 1.3 million deaths worldwide every year ( Figure below ). The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss. The most common cause of lung cancer is exposure to tobacco smoke.
Many cells are invading the surrounding tissue in neoplastic clumps. This corresponds to a poorly differentiated carcinoma.
Physical oncology (PO) is defined as the study of the role of mechanical signals in a cancerous tumor. The mechanical signals can be forces, pressures ("pull", "push" and "shear" designating the forces / pressures that push, pull or are tangential). If we generalize we will speak of "stress field" and "stress tensor".A cancerous tumor (or "solid tumor" in the jargon of oncologists to differentiate them from hematological malignancies) is an organ consisting of two tissues: in the center the cancerous tumor proper and around the ExtraCellular Matrix (ECM), sometimes called stroma, chorion or connective tissue. The concept of connective tissue is interesting because it defines a tissue that travels the entire organism (except the brain) and is a preferred transmitter of mechanical signals.
cancer – a group of diseases in which cells are aggressive (grow and divide without respect to normal limits), invasive (invade and destroy adjacent tissues), and sometimes metastatic (spread to other locations in the body). capillary action (wicking) – water drawn through a medium by surface tension.
We are only considering cancers derived from "epithelia", that is to say the tissue that covers the organs in their interfaces with air, liquids ... or the outside world. Epithelial cells are contiguous and polarized. More than 90% of cancers (breast, prostate, colon / rectum, bronchi, pancreas, etc.) arise from these epithelia after a long process of cancerization.
Cancers are classified by the type of cell that the tumor cells resemble and is therefore presumed to be the origin of the tumor. These types include: Carcinoma: Cancers derived from epithelial cells. This group includes many of the most common cancers and include nearly all those in the breast, prostate, lung, pancreas and colon. Sarcoma: Cancers arising from connective tissue (i.e. bone, cartilage, fat, nerve), each of which develops from cells originating in mesenchymal cells outside the bone marrow.
|
What is the major intracellular cation?
|
[
"magnesium",
"sodium",
"potassium",
"glucose"
] |
C
|
Potassium Potassium is the major intracellular cation. It helps establish the resting membrane potential in neurons and muscle fibers after membrane depolarization and action potentials. In contrast to sodium, potassium has very little effect on osmotic.
In its adult phase, R. pachyptila lacks a digestive system. To provide its energetic needs, it retains those dissolved inorganic nutrients (sulfide, carbon dioxide, oxygen, nitrogen) into its plume and transports them through a vascular system to the trophosome, which is suspended in paired coelomic cavities and is where the intracellular symbiotic bacteria are found. The trophosome is a soft tissue that runs through almost the whole length of the tube's coelom.
The body's circulatory system transports the oxygen to the cells, where cellular respiration takes place.Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide.
While cells expend energy to transport ions and establish a transmembrane potential, they use this potential in turn to transport other ions and metabolites such as sugar. The transmembrane potential of the mitochondria drives the production of ATP, which is the common currency of biological energy. Cells may draw on the energy they store in the resting potential to drive action potentials or other forms of excitation. These changes in the membrane potential enable communication with other cells (as with action potentials) or initiate changes inside the cell, which happens in an egg when it is fertilized by a sperm.
In the process of cation attachment, cations (typically H+ or Na+) attach themselves to analyte molecules; the desorption of the cation attachment (e.g., MNa+) can then be realized through the emitter heating and high field. The ionization of more polar organic molecules (e.g., ones with aliphatic hydroxyl or amino groups) in FD-MS typically go through this mechanism.
The extracellular domain has 157 amino acids and is rich in cysteine residues. The transmembrane and cytoplasmic domains have 17 and 145 amino acids respectively. Exons 1 through 5 encode the extracellular region. Exon 6 encodes the transmembrane region. Exons 7-9 encode the intracellular region.
|
The enzyme pepsin plays an important role in the digestion of proteins by breaking down intact protein to what short-chain amino acids?
|
[
"protons",
"proteins",
"peptides",
"lipids"
] |
C
|
Protein A large part of protein digestion takes place in the stomach. The enzyme pepsin plays an important role in the digestion of proteins by breaking down the intact protein to peptides, which are short chains of four to nine amino acids. In the duodenum, other enzymes— trypsin, elastase, and chymotrypsin—act on the peptides reducing them to smaller peptides. Trypsin elastase, carboxypeptidase, and chymotrypsin are produced by the pancreas and released into the duodenum where they act on the chyme. Further breakdown of peptides to single amino acids is aided by enzymes called peptidases (those that break down peptides). Specifically, carboxypeptidase, dipeptidase, and aminopeptidase play important roles in reducing the peptides to free amino acids. The amino acids are absorbed into the bloodstream through the small intestines. The steps in protein digestion are summarized in Figure 34.17 and Table 34.6.
Using this technique the resolution of deuterium exchange is determined by the size of the peptides produced during digestion. Pepsin, an acid protease, is commonly used for proteolysis, as the quench pH must be maintained during the proteolytic reaction. To minimize the back-exchange, proteolysis and subsequent mass spectrometry analysis must be done as quickly as possible.
While the amino acid members of the triad are located far from one another on the sequence of the protein, due to folding, they will be very close to one another in the heart of the enzyme. The particular geometry of the triad members are highly characteristic to their specific function: it was shown that the position of just four points of the triad characterize the function of the containing enzyme.In the event of catalysis, an ordered mechanism occurs in which several intermediates are generated. The catalysis of the peptide cleavage can be seen as a ping-pong catalysis, in which a substrate binds (in this case, the polypeptide being cleaved), a product is released (the N-terminus "half" of the peptide), another substrate binds (in this case, water), and another product is released (the C-terminus "half" of the peptide).
Once a polypeptide chain is fully folded, it is called a protein. Often many subunits will combine to make a fully functional protein although physiological proteins do exist that contain only one polypeptide chain. Proteins may also incorporate other molecules such as the heme group in hemoglobin, a protein responsible for carrying oxygen in the blood.
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in many biological functions, including digestion of ingested proteins, protein catabolism (breakdown of old proteins), and cell signaling. In the absence of functional accelerants, proteolysis would be very slow, taking hundreds of years. Proteases can be found in all forms of life and viruses. They have independently evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms.
Many scientists observed that enzymatic activity was associated with proteins, but others (such as Nobel laureate Richard Willstätter) argued that proteins were merely carriers for the true enzymes and that proteins per se were incapable of catalysis. In 1926, James B. Sumner showed that the enzyme urease was a pure protein and crystallized it; he did likewise for the enzyme catalase in 1937. The conclusion that pure proteins can be enzymes was definitively demonstrated by John Howard Northrop and Wendell Meredith Stanley, who worked on the digestive enzymes pepsin (1930), trypsin and chymotrypsin.
|
What remains a constant of radioactive substance over time?
|
[
"temperature",
"rate of decay",
"volatility",
"acidity"
] |
B
|
The rate of decay of a radioactive substance is constant over time.
Owens and found that a sample of radioactive material of any size invariably took the same amount of time for half the sample to decay (in this case, 111⁄2 minutes), a phenomenon for which he coined the term "half-life. "Rutherford and Soddy published their "Law of Radioactive Change" to account for all their experiments. Until then, atoms were assumed to be the indestructible basis of all matter and although Curie had suggested that radioactivity was an atomic phenomenon, the idea of the atoms of radioactive substances breaking up was a radically new idea.
The SI measurement quantity of source activity is the Becquerel, though the historical unit Curies is still in partial use, such as in the USA, despite their NIST strongly advising the use of the SI unit. The SI unit for health purposes is mandatory in the EU. An irradiation source typically lasts for between 5 and 15 years before its activity drops below useful levels. However sources with long half-life radionuclides when utilised as calibration sources can be used for much longer.
Trace quantities are found in nature from neutron capture reactions by uranium atoms, a fact not discovered until 1951.Twenty-five neptunium radioisotopes have been characterized, with the most stable being 237Np with a half-life of 2.14 million years, 236Np with a half-life of 154,000 years, and 235Np with a half-life of 396.1 days. All of the remaining radioactive isotopes have half-lives that are less than 4.5 days, and the majority of these have half-lives that are less than 50 minutes. This element also has five meta states, with the most stable being 236mNp (t1/2 22.5 hours).
During the first 40 years that nuclear waste was being created in the United States, no legislation was enacted to manage its disposal. Nuclear waste, some of which remains radioactive with a half-life of more than one million years, was kept in various types of temporary storage. Of particular concern during nuclear waste disposal are two long-lived fission products, Tc-99 (half-life 220,000 years) and I-129 (half-life 17 million years), which dominate spent fuel radioactivity after a few thousand years. The most troublesome transuranic elements in spent fuel are Np-237 (half-life two million years) and Pu-239 (half-life 24,000 years).Most existing nuclear waste came from production of nuclear weapons.
Time constants are a feature of the lumped system analysis (lumped capacity analysis method) for thermal systems, used when objects cool or warm uniformly under the influence of convective cooling or warming.Physically, the time constant represents the elapsed time required for the system response to decay to zero if the system had continued to decay at the initial rate, because of the progressive change in the rate of decay the response will have actually decreased in value to 1 / e ≈ 36.8% in this time (say from a step decrease). In an increasing system, the time constant is the time for the system's step response to reach 1 − 1 / e ≈ 63.2% of its final (asymptotic) value (say from a step increase). In radioactive decay the time constant is related to the decay constant (λ), and it represents both the mean lifetime of a decaying system (such as an atom) before it decays, or the time it takes for all but 36.8% of the atoms to decay. For this reason, the time constant is longer than the half-life, which is the time for only 50% of the atoms to decay.
|
Terrestrial ecosystems, also known for their diversity, are grouped into large categories called what?
|
[
"bisomes",
"monomes",
"biomes",
"substrates"
] |
C
|
Terrestrial ecosystems, also known for their diversity, are grouped into large categories called biomes. A biome is a largescale community of organisms, primarily defined on land by the dominant plant types that exist in geographic regions of the planet with similar climatic conditions. Examples of biomes include tropical rainforests, savannas, deserts, grasslands, temperate forests, and tundras. Grouping these ecosystems into just a few biome categories obscures the great diversity of the individual ecosystems within them. For example, the saguaro cacti (Carnegiea gigantean) and other plant life in the Sonoran Desert, in the United States, are relatively diverse compared with the desolate rocky desert of Boa Vista, an island off the coast of Western Africa (Figure 20.3).
The use of the term ecoregion is an outgrowth of a surge of interest in ecosystems and their functioning. In particular, there is awareness of issues relating to spatial scale in the study and management of landscapes. It is widely recognized that interlinked ecosystems combine to form a whole that is "greater than the sum of its parts". There are many attempts to respond to ecosystems in an integrated way to achieve "multi-functional" landscapes, and various interest groups from agricultural researchers to conservationists are using the "ecoregion" as a unit of analysis. The "Global 200" is the list of ecoregions identified by WWF as priorities for conservation.
Ecology (from Greek: οἶκος, "house", or "environment"; -λογία, "study of") is a branch of biology concerning interactions among organisms and their biophysical environment, which includes both biotic and abiotic components. Topics of interest include the biodiversity, distribution, biomass, and populations of organisms, as well as cooperation and competition within and between species. Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, pedogenesis, nutrient cycling, and niche construction, regulate the flux of energy and matter through an environment. These processes are sustained by organisms with specific life history traits.
Plants are distributed almost worldwide. While they inhabit several biomes which can be divided into a multitude of ecoregions, only the hardy plants of the Antarctic flora, consisting of algae, mosses, liverworts, lichens, and just two flowering plants, have adapted to the prevailing conditions on that southern continent.Plants are often the dominant physical and structural component of the habitats where they occur. Many of the Earth's biomes are named for the type of vegetation because plants are the dominant organisms in those biomes, such as grassland, savanna, and tropical rainforest.
The scale of ecological dynamics can operate like a closed system, such as aphids migrating on a single tree, while at the same time remaining open with regard to broader scale influences, such as atmosphere or climate. Hence, ecologists classify ecosystems hierarchically by analyzing data collected from finer scale units, such as vegetation associations, climate, and soil types, and integrate this information to identify emergent patterns of uniform organization and processes that operate on local to regional, landscape, and chronological scales. To structure the study of ecology into a conceptually manageable framework, the biological world is organized into a nested hierarchy, ranging in scale from genes, to cells, to tissues, to organs, to organisms, to species, to populations, to communities, to ecosystems, to biomes, and up to the level of the biosphere. This framework forms a panarchy and exhibits non-linear behaviors; this means that "effect and cause are disproportionate, so that small changes to critical variables, such as the number of nitrogen fixers, can lead to disproportionate, perhaps irreversible, changes in the system properties. ": 14
The set of environmental features essential to that species' survival, is its "niche." (Ecology. Begon, Harper, Townsend)
|
High explosives create shock waves that exceed the speed of sound, a phenomenon that goes by what term?
|
[
"light speed",
"ion speed",
"turbulence",
"supersonic"
] |
D
|
The modern day formulation of gun powder is called black powder. It is still commonly used today. Its formulation is still quite similar to what was used in 9 th century China. Black powder is considered a low explosive. It is a mixture that burns quickly, but the resulting shock wave travels at subsonic speeds. The speed at which it burns is dependent on the accessibility of oxygen atoms to the carbon source. In contrast, high explosives like nitroglycerin detonate instead of burning, creating shock waves that are supersonic (faster than the speed of sound).
Usually consists of a shock wave propagating into a stationary medium In this case, the gas ahead of the shock is stationary (in the laboratory frame) and the gas behind the shock can be supersonic in the laboratory frame. The shock propagates with a wavefront which is normal (at right angles) to the direction of flow. The speed of the shock is a function of the original pressure ratio between the two bodies of gas. Moving shocks are usually generated by the interaction of two bodies of gas at different pressure, with a shock wave propagating into the lower pressure gas and an expansion wave propagating into the higher pressure gas. Examples: Balloon bursting, Shock tube, shock wave from explosion.
However, they require facilities and expert personnel for handling high explosives. Also, in addition to the initial pressure wave, a jet effect caused by the expansion of compressed gases (compression-driven) or production of rapidly expanding gases (blast-driven) follows and may transfer momentum to a sample after the blast wave has passed.
This is a compilation of published detonation velocities for various high explosive compounds. Detonation velocity is the speed with which the detonation shock wave travels through the explosive. It is a key, directly measurable indicator of explosive performance, but depends on density which must always be specified, and may be too low if the test charge diameter is not large enough. Especially for little studied explosives there may be divergent published values due to charge diameter issues.
An explosion is a type of spontaneous chemical reaction that, once initiated, is driven by both a large exothermic change (great release of heat) and a large positive entropy change (great quantities of gases are released) in going from reactants to products, thereby constituting a thermodynamically favorable process in addition to one that propagates very rapidly. Thus, explosives are substances that contain a large amount of energy stored in chemical bonds. The energetic stability of the gaseous products and hence their generation comes from the formation of strongly bonded species like carbon monoxide, carbon dioxide, and (di)nitrogen, which contain strong double and triple bonds having bond strengths of nearly 1 MJ/mole. Consequently, most commercial explosives are organic compounds containing –NO2, –ONO2 and –NHNO2 groups that, when detonated, release gases like the aforementioned (e.g., nitroglycerin, TNT, HMX, PETN, nitrocellulose).An explosive is classified as a low or high explosive according to its rate of combustion: low explosives burn rapidly (or deflagrate), while high explosives detonate.
When a person has a shock wave, not only is the eardrum ruptured, but also has ossicular discontinuities. The explosion or blast if powerful can cause traumatic brain injury.
|
What do you call a structure composed of two or more types of tissues that work together to do a specific task?
|
[
"cell",
"marrow",
"organ",
"system"
] |
C
|
An organ is a structure composed of two or more types of tissues that work together to do a specific task. Most modern plants have several organs that help them survive and reproduce in a variety of habitats. Major organs of most plants include roots, stems, and leaves. These and other plant organs generally contain all three major tissue types.
OpenStructures works at several scales, and analogies are made to biological systems including (from smallest to biggest): Parts, like body tissues. Components, like organs, formed by the functional grouping together of multiple tissues. An example is a motor. Structures, like a group of related organs in an organ system.
Other types of structures used are:
The third approach of bioprinting is a combination of both the biomimicry and self-assembly approaches, which is called mini tissues. Organs and tissues are built from very small functional components. Mini-tissue approach takes these small pieces and manufacture and arrange them into larger framework.
The cardiac skeleton is made of dense connective tissue which gives structure to the heart by forming the atrioventricular septum—which separates the atria from the ventricles—and the fibrous rings which serve as bases for the four heart valves. Collagen extensions from the valve rings seal and limit electrical activity of the atria from influencing electrical pathways that cross the ventricles.
Fibromuscular tissue is made up of fibrous tissue and muscular tissue. New vascularised connective tissue that forms in the process of wound healing is termed granulation tissue. All of the special connective tissue types have been included as a subset of fascia in the fascial system, with blood and lymph classed as liquid fascia.Bone and cartilage can be further classified as supportive connective tissue. Blood and lymph can also be categorized as fluid connective tissue, and liquid fascia.
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.