Question: What is the correct order of events?

Choices:
- A. Chloride channels are defective or absent, then children inherit two recessive alleles of cystic fibrosis, then mucus builds up
- B. Children inherit two recessive alleles of cystic fibrosis, then chloride channels are defective or absent, then mucus builds up

Prompt: Given the context, pick the right choice that answers the question


Context: The original cell produces a copy of its chromosome and surrounds it with a tough multilayered structure, forming the endospore. Water is removed from the endospore, and its metabolism halts. The original cell then lyses, releasing the endospore.

Question: What would happen if the cell did not lyse?

Choices:
- A. The endospore would not be released
- B. water would not be removed from the endospore

Prompt: Given the context, pick the right choice that answers the question


Question: The endospore's metabolism halts

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: What will not happen if the original cell does not lyse?

Choices:
- A. endospore is not released
- B. metabolism halts

Prompt: Given the context, pick the right choice that answers the question


Context: In E. coli, a pilus of the donor cell attaches to the recipient (Figure 27.12). The pilus then retracts, pulling the two cells together, much like a grappling hook. The next step is thought to be the formation of a temporary "mating bridge" between the two cells, through which the donor may transfer DNA to the recipient.

Question: What would happen without the "mating bridge"?

Choices:
- A. the donor will not transfer DNA to the recipient
- B. the pilus will not retract

Prompt: Given the context, pick the right choice that answers the question


Question: what is the correct order of events?

Choices:
- A. a pilus of a donor cell attaches to the recipient, then the donor may transfer DNA to the recipient, then the pilus retracts
- B. a pilus of a donor cell attaches to the recipient, then the pilus retracts, then the donor may transfer DNA to the recipient

Prompt: Given the context, pick the right choice that answers the question


Context: One way a triploid cell may arise is by the fertilization of an abnormal diploid egg produced by nondisjunction of all its chromosomes. Tetraploidy could result from the failure of a 2n zygote to divide after replicating its chromosomes. Subsequent normal mitotic divisions would then produce a 4n embryo.

Question: What can cause a triploid cell?

Choices:
- A. fertilization of an abnormal diploid egg
- B. failure of a 2n zygote to divide after replicating its chromosomes

Prompt: Given the context, pick the right choice that answers the question


Question: Tetraploidy involves a 4n embryo

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: Fertilization of an abnormal diploid egg produced by nondisjunction of all its chromosomes results in what?

Choices:
- A. Tetraploidy
- B. a triploid cell

Prompt: Given the context, pick the right choice that answers the question


Context: We imagine that prior to duplication the hydrogen bonds are broken, and the two chains unwind and separate. Each chain then acts as a template for the formation onto itself of a new companion chain, so that eventually we shall have two pairs of chains, where we only had one before. Moreover, the sequence of the pairs of bases will have been duplicated exactly.

Question: The companion chain acts as a template

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen if the two chains did not unwind and separate?

Choices:
- A. Hydrogen bonds would not be broken
- B. duplication would not occur

Prompt: Given the context, pick the right choice that answers the question


Question: Which events can occur at the same time?

Choices:
- A. duplication and the hydrogen bonds are broken
- B. the two chains unwind and separate

Prompt: Given the context, pick the right choice that answers the question


Context: In many cases, a segment of the strand containing the damage is cut out (excised) by a DNA-cutting enzyme: a nuclease: and the resulting gap is then filled in with nucleotides, using the undamaged strand as a template. The enzymes involved in filling the gap are a DNA polymerase and DNA ligase. One such DNA repair system is called nucleotide excision repair (Figure 16.19).

Question: A segment of the strand containing the damage is cut out by what?

Choices:
- A. nucleotides
- B. a nuclease

Prompt: Given the context, pick the right choice that answers the question


Question: DNA polymerase and DNA ligase fill the gap with nucleotides

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: When a segment of the strand containing the damage is cut out, what is produced?

Choices:
- A. a nuclease
- B. a gap

Prompt: Given the context, pick the right choice that answers the question


Context: Sickle-cell disease is caused by the substitution of a single amino acid in the hemoglobin protein of red blood cells; in homozygous individuals, all hemoglobin is of the sickle-cell (abnormal) variety. When the oxygen content of an affected individual's blood is low (at high altitudes or under physical stress, for instance), the sickle-cell hemoglobin molecules aggregate into long rods that deform the red cells into a sickle shape (see Figure 5.21). Sickled cells may clump and clog small blood vessels, often leading to other symptoms throughout the body, including physical weakness, pain, organ damage, and even paralysis.

Question: What would happen without the substitution of a single amino acid?

Choices:
- A. Hemoglobin protein would not be produced
- B. Sickle-cell disease would not occur

Prompt: Given the context, pick the right choice that answers the question


Question: Which entity is responsible for sickle-cell disease?

Choices:
- A. Hemoglobin
- B. small blood vessels

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen if hemoglobin molecules did not aggregate into long rods?

Choices:
- A. red cells do not deform into a sickle shape
- B. Oxygen content of an individual's blood does not become low.

Prompt: Given the context, pick the right choice that answers the question


Question: Homozygous individuals can have paralysis

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Context: Each mammalian Toll-like receptor (TLR) binds to fragments of molecules characteristic of a set of pathogens (Figure 43.6). In each case, the recognized macromolecule is normally absent from the vertebrate body and is an essential component of certain groups of pathogens. After detecting invading pathogens, a phagocytic cell engulfs them, trapping them in a vacuole. The vacuole then fuses with a lysosome (see Figure 43.3), leading to destruction of the invaders in two ways. First, gases produced in the lysosome poison the engulfed pathogens. Second, lysozyme and other enzymes in the lysosome degrade the components of the pathogens.

Question: What is the result of gasses being produced in the lysosome?

Choices:
- A. engulfed pathogens are poisoned
- B. degradation of the components of the pathogens

Prompt: Given the context, pick the right choice that answers the question


Question: The Toll-like receptor binds to what?

Choices:
- A. a macromolecule that is normally absent from the vertebrate body
- B. a phagocytic cell

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen if the vacuole did not fuse with a lysosome?

Choices:
- A. Destruction of invaders would not occur
- B. pathogens would not be trapped in a vacuole

Prompt: Given the context, pick the right choice that answers the question


Question: Phagocytic cells trap invading pathogens in a vacuole

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Context: Histamine released at sites of damage triggers nearby blood vessels to dilate and become more permeable. Activated macrophages and neutrophils discharge cytokines, signaling molecules that enhance an immune response. These cytokines promote blood flow to the site of injury or infection. The increase in local blood supply causes the redness and increased skin temperature typical of the inflammatory response. Blood-engorged capillaries leak fluid into neighboring tissues, causing swelling. During inflammation, cycles of signaling and response transform the site. Activated complement proteins promote further release of histamine, attracting more phagocytic cells that enter injured tissues (see Figure 43.8) and carry out additional phagocytosis. At the same time, enhanced blood flow to the site helps deliver antimicrobial peptides. The result is an accumulation of pus, a fluid rich in white blood cells, dead pathogens, and cell debris from damaged tissue.

Question: What is the correct order of events?

Choices:
- A. Damage causes release of histamine, which triggers nearby blood vessels to dilate.
- B. Histamine causes damage, which triggers nearby blood vessels to dilate

Prompt: Given the context, pick the right choice that answers the question


Question: Which events can happen at the same time?

Choices:
- A. enhanced blood flow to the site helps deliver antimicrobial peptides and histamine is released
- B. enhanced blood flow to the site helps deliver antimicrobial peptides and phagocytosis

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen if capillaries did not leak fluid into neighboring tissues?

Choices:
- A. Swelling would not occur
- B. Neutrophils would not discharge cytokines

Prompt: Given the context, pick the right choice that answers the question


Question: Sites of damage result in an inflammatory response

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen without activated complement?

Choices:
- A. Additional phagocytosis would not occur
- B. histamine release would not occur

Prompt: Given the context, pick the right choice that answers the question


Context: Recognition of protein antigens by T cells begins when a pathogen or part of a pathogen either infects or is taken in by a host cell (Figure 43.12a). Inside the host cell, enzymes in the cell cleave the antigen into smaller peptides. Each peptide, called an antigen fragment, then binds to an MHC molecule inside the cell. Movement of the MHC molecule and bound antigen fragment to the cell surface results in antigen presentation, the display of the antigen fragment in an exposed groove of the MHC protein. Figure 43.12b shows a close-up view of antigen presentation, which advertises the fact that a host cell contains a foreign substance. If the cell displaying an antigen fragment encounters a T cell with the right specificity, the antigen receptor on the T cell can bind to both the antigen fragment and the MHC molecule.

Question: What would happen if the MHC molecule did not move to the cell surface?

Choices:
- A. The cell would not encounter a T-cell with the right specificity
- B. Figure 43.12b would not show a close-up view

Prompt: Given the context, pick the right choice that answers the question


Question: Which event occurs first?

Choices:
- A. a pathogen or part of a pathogen either infects or is taken in by a host cell
- B. Recognition of protein antigens by T cells

Prompt: Given the context, pick the right choice that answers the question


Question: Antigen presentation is necessary for the T cell to bind to both the antigen fragment and the MHC molecule

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Context: The rearranged genes are transcribed, and the transcripts are processed for translation. Following translation, the light chain and heavy chain assemble together, forming an antigen receptor (see Figure 43.13). Each pair of randomly rearranged heavy and light chains results in a different antigen-binding site.

Question: What is processed for translation?

Choices:
- A. The transcripts
- B. The rearranged genes

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen without translation?

Choices:
- A. an antigen receptor would not be formed
- B. The rearranged genes would not be transcribed

Prompt: Given the context, pick the right choice that answers the question


Question: What is formed when the light chain and the heavy chain assemble together?

Choices:
- A. An antigen receptor
- B. rearranged genes

Prompt: Given the context, pick the right choice that answers the question


Context: In response to a specific antigen and to immune cell signals (not shown), one B cell divides and forms a clone of cells. The remaining B cells, which have antigen receptors specific for other antigens, do not respond. The clone of cells formed by the selected B cell gives rise to memory B cells and antibody-secreting plasma cells.

Question: Antibody-secreting plasma cells are produced in response to what?

Choices:
- A. memory B cells
- B. a specific antigen and immune cell signals

Prompt: Given the context, pick the right choice that answers the question


Question: In response to a specific antigen and to immune cell signals, one B cell produces what?

Choices:
- A. other antigens
- B. memory B cells and antibody-secreting plasma cells

Prompt: Given the context, pick the right choice that answers the question


Question: The remaining B cells are necessary to produce memory B cells and antibody-secreting plasma cells

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Context: The antigen receptors on the surface of the helper T cell bind to the antigen fragment and to the class II MHC molecule displaying that fragment on the antigen-presenting cell. At the same time, an accessory protein on the helper T cell surface binds to the class II MHC molecule, helping keep the cells joined. As the two cells interact, signals in the form of cytokines are exchanged in both directions.

Question: What binds to the antigen fragment and to the class II MHC molecule?

Choices:
- A. The surface of the helper T cell
- B. The antigen receptors

Prompt: Given the context, pick the right choice that answers the question


Question: The accessory protein binds to the antigen fragment and to the class II MHC molecule

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: What two entities exchange signals in the form of cytokines?

Choices:
- A. an accessory protein and the helper T cell
- B. The helper T cell and the antigen-presenting cell

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen without the accessory molecule?

Choices:
- A. The MHC molecule would not display the fragment
- B. helping keep the cells joined would not occur

Prompt: Given the context, pick the right choice that answers the question


Context: In a light microscope (LM), visible light is passed through the specimen and then through glass lenses. The lenses refract (bend) the light in such a way that the image of the specimen is magnified as it is projected into the eye or into a camera (see Appendix D).

Question: What would happen without the specimen?

Choices:
- A. the image of the specimen would not be projected
- B. lenses would not refract the light

Prompt: Given the context, pick the right choice that answers the question


Question: What is the correct order of events?

Choices:
- A. light passes through the specimen, then light passes through glass lenses
- B. lenses refract the light, then visible light passes through the specimen

Prompt: Given the context, pick the right choice that answers the question


Question: The specimen refracts the light

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Context: As we described in Chapter 6, the cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane; this process is called exocytosis. A transport vesicle that has budded from the Golgi apparatus moves along microtubules of the cytoskeleton to the plasma membrane. When the vesicle membrane and plasma membrane come into contact, specific proteins rearrange the lipid molecules of the two bilayers so that the two membranes fuse. The contents of the vesicle then spill to the outside of the cell, and the vesicle membrane becomes part of the plasma membrane (see Figure 7.12, step 4).

Question: The Golgi apparatus moves along microtubules

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: Which event occurs first?

Choices:
- A. The cell secretes certain biological molecules
- B. a transport vesicle moves along microtubules

Prompt: Given the context, pick the right choice that answers the question


Question: The transport vesicle membrane fuses with the plasma membrane

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Context: How does NAD+ trap electrons from glucose and other organic molecules? Enzymes called dehydrogenases remove a pair of hydrogen atoms (2 electrons and 2 protons) from the substrate (glucose, in this example), thereby oxidizing it. The enzyme delivers the 2 electrons along with 1 proton to its coenzyme, NAD+ (Figure 9.4). The other proton is released as a hydrogen ion (H+) into the surrounding solution. By receiving 2 negatively charged electrons but only 1 positively charged proton, NAD+ has its charge neutralized when it is reduced to NADH. The name NADH shows the hydrogen that has been received in the reaction. NAD+ is the most versatile electron acceptor in cellular respiration and functions in several of the redox steps during the breakdown of glucose.

Question: Which molecule receives only 1 positively charged proton?

Choices:
- A. NADH
- B. NAD+

Prompt: Given the context, pick the right choice that answers the question


Question: A dehydrogenase delivers the 2 electrons along along with 1 proton to its coenzyme

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: What happens to the 2 electrons?

Choices:
- A. released into the surrounding solution
- B. delivered to NAD+

Prompt: Given the context, pick the right choice that answers the question


Context: A small area of the plasma membrane sinks inward to form a pocket. As the pocket deepens, it pinches in, forming a vesicle containing material that had been outside the cell.

Question: The plasma membrane had been outside the cell

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Question: What happens because the pocket deepens?

Choices:
- A. The plasma membrane sinks
- B. A vesicle containing material is formed

Prompt: Given the context, pick the right choice that answers the question


Context: In most enzymatic reactions, the substrate is held in the active site by so-called weak interactions, such as hydrogen bonds and ionic bonds. R groups of a few of the amino acids that make up the active site catalyze the conversion of substrate to product, and the product departs from the active site. The enzyme is then free to take another substrate molecule into its active site.

Question: What catalyzes the conversion of substrate to product?

Choices:
- A. Ionic bonds
- B. R groups

Prompt: Given the context, pick the right choice that answers the question


Question: Which event occurs first?

Choices:
- A. the substrate is held in the active site by hydrogen bonds and ionic bonds
- B. conversion of substrate to product

Prompt: Given the context, pick the right choice that answers the question


Question: what would happen if the product did not depart from the active site?

Choices:
- A. The enzyme would not be free to take another substrate molecule into its active site
- B. R groups would not catalyze the conversion of substrate to product

Prompt: Given the context, pick the right choice that answers the question


Context: As summarized in Figure 9.8, glycolysis can be divided into two phases: energy investment and energy payoff. During the energy investment phase, the cell actually spends ATP. This investment is repaid with interest during the energy payoff phase, when ATP is produced by substrate-level phosphorylation and NAD+ is reduced to NADH by electrons released from the oxidation of glucose. The net energy yield from glycolysis, per glucose molecule, is 2 ATP plus 2 NADH. The ten steps of the glycolytic pathway are shown in Figure 9.9.

Question: What would happen without the oxidation of glucose?

Choices:
- A. NAD+ would not be reduced to NADH
- B. ATP would not be produced

Prompt: Given the context, pick the right choice that answers the question


Question: Which event is part of the energy investment phase?

Choices:
- A. the cell actually spends ATP
- B. the energy payoff phase

Prompt: Given the context, pick the right choice that answers the question


Question: Substrate-level phosphorylation is necessary to produce NADH

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: Which of the following happens first?

Choices:
- A. Energy payoff
- B. Energy investment

Prompt: Given the context, pick the right choice that answers the question


Context: New layers of sediment cover older ones and compress them into superimposed layers of rock called strata (singular, stratum). The fossils in a particular stratum provide a glimpse of some of the organisms that populated Earth at the time that layer formed. Later, erosion may carve through upper (younger) strata, revealing deeper (older) strata that had been buried.

Question: What would happen if new layers of sediment did not cover older ones?

Choices:
- A. Strata would not form
- B. Erosion would not occur

Prompt: Given the context, pick the right choice that answers the question


Question: Newer layers are upper strata

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Context: The first step is carried out by an enzyme present only in mesophyll cells called PEP carboxylase. This enzyme adds CO2 to phosphoenolpyruvate (PEP), forming the four-carbon product oxaloacetate. PEP carboxylase has a much higher affinity for CO2 than does rubisco and no affinity for O2. Therefore, PEP carboxylase can fix carbon efficiently when rubisco cannot: that is, when it is hot and dry and stomata are partially closed, causing CO2 concentration in the leaf to fall and O2 concentration to rise. After the C4 plant fixes carbon from CO2, the mesophyll cells export their four-carbon products (malate in the example shown in Figure 10.20) to bundle-sheath cells through plasmodesmata (see Figure 6.31). Within the bundle-sheath cells, the four-carbon compounds release CO2, which is reassimilated into organic material by rubisco and the Calvin cycle. The same reaction regenerates pyruvate, which is transported to mesophyll cells. There, ATP is used to convert pyruvate to PEP, allowing the reaction cycle to continue; this ATP can be thought of as the "price" of concentrating CO2 in the bundle-sheath cells. To generate this extra ATP, bundle-sheath cells carry out cyclic electron flow, the process described earlier in this chapter (see Figure 10.16). In fact, these cells contain PS I but no PS II, so cyclic electron flow is their only photosynthetic mode of generating ATP.

Question: What adds CO2 to PEP?

Choices:
- A. PEP carboxylase
- B. oxaloacetate

Prompt: Given the context, pick the right choice that answers the question


Question: Which enzyme cannot fix carbon when CO2 concentration in the leaf falls and O2 concentration rises?

Choices:
- A. rubisco
- B. PEP carboxylase

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen without plasmodesmata?

Choices:
- A. mesophyll cells could not export their four-carbon products to bundle-sheath cells
- B. The C4 plant could not fix carbon from CO2

Prompt: Given the context, pick the right choice that answers the question


Question: What is required to produce ATP in bundle-sheath cells?

Choices:
- A. PS II
- B. electron flow

Prompt: Given the context, pick the right choice that answers the question


Context: A second photosynthetic adaptation to arid conditions has evolved in many succulent (water-storing) plants, numerous cacti, pineapples, and representatives of several other plant families. These plants open their stomata during the night and close them during the day, just the reverse of how other plants behave. Closing stomata during the day helps desert plants conserve water, but it also prevents CO2 from entering the leaves. During the night, when their stomata are open, these plants take up CO2 and incorporate it into a variety of organic acids. This mode of carbon fixation is called crassulacean acid metabolism, or CAM, after the plant family Crassulaceae, the succulents in which the process was first discovered. The mesophyll cells of CAM plants store the organic acids they make during the night in their vacuoles until morning, when the stomata close. During the day, when the light reactions can supply ATP and NADPH for the Calvin cycle, CO2 is released from the organic acids made the night before to become incorporated into sugar in the chloroplasts. Figure 10.21 C4 and CAM photosynthesis compared. Both adaptations are characterized by A; preliminary incorporation of CO2 into organic acids, followed by B; transfer of CO2 to the Calvin cycle. The C4 and CAM pathways are two evolutionary solutions to the problem of maintaining photosynthesis with stomata partially or completely closed on hot, dry days.

Question: Other plants open their stomata during the night and close them during the day.

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: succulents make organic acids during the night

Choices:
- A. True
- B. False

Prompt: Given the context, pick the right choice that answers the question


Question: What is incorporated into sugar in the chloroplasts?

Choices:
- A. CO2
- B. Organic acids

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen without vacuoles?

Choices:
- A. the stomata could not close
- B. plants could not store the organic acids

Prompt: Given the context, pick the right choice that answers the question


Context: Now that we know about the role of cAMP in G protein signaling pathways, we can explain in molecular detail how certain microbes cause disease. Consider cholera, a disease that is frequently epidemic in places where the water supply is contaminated with human feces. People acquire the cholera bacterium, Vibrio cholerae, by drinking contaminated water. The bacteria form a biofilm on the lining of the small intestine and produce a toxin. The cholera toxin is an enzyme that chemically modifies a G protein involved in regulating salt and water secretion. Because the modified G protein is unable to hydrolyze GTP to GDP, it remains stuck in its active form, continuously stimulating adenylyl cyclase to make cAMP. The resulting high concentration of cAMP causes the intestinal cells to secrete large amounts of salts into the intestines, with water following by osmosis. An infected person quickly develops profuse diarrhea and if left untreated can soon die from the loss of water and salts.

Question: What does Vibrio cholerae do?

Choices:
- A. produces a toxin
- B. Drinks contaminated water

Prompt: Given the context, pick the right choice that answers the question


Question: The cholera toxin does what?

Choices:
- A. regulates salt and water secretion
- B. chemically modifies a G protein

Prompt: Given the context, pick the right choice that answers the question


Question: which event occurs first?

Choices:
- A. an infected person quickly develops profuse diarrhea
- B. intestinal cells secrete large amounts of salt into the intestine

Prompt: Given the context, pick the right choice that answers the question


Question: The modified G protein hydrolyzes GTP to GDP

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Context: In animal cells, cytokinesis occurs by a process known as cleavage. The first sign of cleavage is the appearance of a cleavage furrow, a shallow groove in the cell surface near the old metaphase plate (Figure 12.10a). On the cytoplasmic side of the furrow is a contractile ring of actin microfilaments associated with molecules of the protein myosin. The actin microfilaments interact with the myosin molecules, causing the ring to contract. The contraction of the dividing cell's ring of microfilaments is like the pulling of a drawstring. The cleavage furrow deepens until the parent cell is pinched in two, producing two completely separated cells, each with its own nucleus and share of cytosol, organelles, and other subcellular structures.

Question: What is necessary for the appearance of a cleavage furrow?

Choices:
- A. actin microfilaments
- B. the old metaphase plate

Prompt: Given the context, pick the right choice that answers the question


Question: Which entity is part of the contractile ring?

Choices:
- A. the furrow
- B. actin microfilaments

Prompt: Given the context, pick the right choice that answers the question


Question: What is produced by the cleavage furrow deepening?

Choices:
- A. Other subcellular structures
- B. two completely separated cells

Prompt: Given the context, pick the right choice that answers the question


Context: In alcohol fermentation (Figure 9.17a), pyruvate is converted to ethanol (ethyl alcohol) in two steps. The first step releases carbon dioxide from the pyruvate, which is converted to the two-carbon compound acetaldehyde. In the second step, acetaldehyde is reduced by NADH to ethanol. This regenerates the supply of NAD+ needed for the continuation of glycolysis. Many bacteria carry out alcohol fermentation under anaerobic conditions.

Question: Which event occurs first?

Choices:
- A. carbon dioxide is released from the pyruvate
- B. ethanol is produced

Prompt: Given the context, pick the right choice that answers the question


Question: What regenerates the supply of NAD+?

Choices:
- A. The second step
- B. The first step

Prompt: Given the context, pick the right choice that answers the question


Question: Bacteria is produced by alcohol fermentation

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Context: Like an animal cell, the plant cell swells as water enters by osmosis (Figure 7.15b). However, the relatively inelastic wall will expand only so much before it exerts a back pressure on the cell, called turgor pressure, that opposes further water uptake. At this point, the cell is turgid (very firm), which is the healthy state for most plant cells.

Question: What is required for the wall to exert a back pressure on the cell?

Choices:
- A. an animal cell
- B. water

Prompt: Given the context, pick the right choice that answers the question


Question: How does water enter the cell?

Choices:
- A. osmosis
- B. the relatively inelastic wall will expand

Prompt: Given the context, pick the right choice that answers the question


Question: Turgor pressure is caused by and prevents water uptake.

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Context: Methicillin works by deactivating a protein that bacteria use to synthesize their cell walls. However, S. aureus populations exhibited variations in how strongly their members were affected by the drug. In particular, some individuals were able to synthesize their cell walls using a different protein that was not affected by methicillin. These individuals survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common, leading to the spread of MRSA.

Question: Methicillin works directly by deactivating cell walls

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Question: Methicillin allows individuals to reproduce at higher rates

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen without Methicillin?

Choices:
- A. Resistant individuals would not be produced
- B. bacteria would not synthesize cell walls

Prompt: Given the context, pick the right choice that answers the question


Question: What is the correct order of events?

Choices:
- A. Methicillin deactivates a protein, then some individuals use a different protein, then MRSA spreads
- B. Methicillin deactivates a protein, then MRSA spreads, then some individuals use a different protein.

Prompt: Given the context, pick the right choice that answers the question


Context: As a polypeptide chain grows from a bound ribosome, the chain is threaded into the ER lumen through a pore formed by a protein complex in the ER membrane. As the new polypeptide enters the ER lumen, it folds into its native shape.

Question: What would happen if the chain is not threaded into the ER lumen?

Choices:
- A. the new polypeptide would not enter the ER lumen
- B. The protein complex would not be formed

Prompt: Given the context, pick the right choice that answers the question


Question: What folds into its native shape?

Choices:
- A. the new polypeptide
- B. The ER lumen

Prompt: Given the context, pick the right choice that answers the question


Question: The bound ribosome is threaded into the ER lumen

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Context: Amoebas and many other protists eat by engulfing smaller organisms or food particles, a process called phagocytosis (from the Greek phagein, to eat, and kytos, vessel, referring here to the cell). The food vacuole formed in this way then fuses with a lysosome, whose enzymes digest the food (Figure 6.13a, bottom). Digestion products, including simple sugars, amino acids, and other monomers, pass into the cytosol and become nutrients for the cell.

Question: Phagocytosis produces what?

Choices:
- A. the food vacuole
- B. food particles

Prompt: Given the context, pick the right choice that answers the question


Question: What becomes nutrients for the cell?

Choices:
- A. digestion products
- B. enzymes

Prompt: Given the context, pick the right choice that answers the question


Question: The food vacuole digests food

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Context: Sutherland's research team discovered that epinephrine stimulates glycogen breakdown by somehow activating a cytosolic enzyme, glycogen phosphorylase. However, when epinephrine was added to a test-tube mixture containing the enzyme and its substrate, glycogen, no breakdown occurred. Epinephrine could activate glycogen phosphorylase only when the hormone was added to a solution containing intact cells.

Question: What is required for epinephrine to activate glycogen phosphorylase?

Choices:
- A. intact cells
- B. a test-tube mixture

Prompt: Given the context, pick the right choice that answers the question


Question: What directly causes breakdown of glycogen?

Choices:
- A. epinephrine
- B. glycogen phosphorylase

Prompt: Given the context, pick the right choice that answers the question


Context: Reception. Reception is the target cell's detection of a signaling molecule coming from outside the cell. A chemical signal is "detected" when the signaling molecule binds to a receptor protein located at the cell's surface or inside the cell. Transduction. The binding of the signaling molecule changes the receptor protein in some way, initiating the process of transduction. The transduction stage converts the signal to a form that can bring about a specific cellular response. In Sutherland's system, the binding of epinephrine to a receptor protein in a liver cell's plasma membrane leads to activation of glycogen phosphorylase. Transduction sometimes occurs in a single step but more often requires a sequence of changes in a series of different molecules: a signal transduction pathway. The molecules in the pathway are often called relay molecules. Response. In the third stage of cell signaling, the transduced signal finally triggers a specific cellular response. The response may be almost any imaginable cellular activity: such as catalysis by an enzyme (for example, glycogen phosphorylase), rearrangement of the cytoskeleton, or activation of specific genes in the nucleus. The cell-signaling process helps ensure that crucial activities like these occur in the right cells, at the right time, and in proper coordination with the activities of other cells of the organism. We'll now explore the mechanisms of cell signaling in more detail, including a discussion of fine-tuning and termination of the process.

Question: What is required for reception?

Choices:
- A. glycogen phosphorylase
- B. a receptor

Prompt: Given the context, pick the right choice that answers the question


Question: What is required for transduction?

Choices:
- A. reception
- B. response

Prompt: Given the context, pick the right choice that answers the question


Question: Epinephrine acts as what?

Choices:
- A. A signaling molecule
- B. a receptor

Prompt: Given the context, pick the right choice that answers the question


Question: What do relay molecules do?

Choices:
- A. signal transduction
- B. almost any imaginable cellular activity

Prompt: Given the context, pick the right choice that answers the question


Context: Cells of mating type a secrete a signaling molecule called a factor, which can bind to specific receptor proteins on nearby cells. At the same time, cells secrete factor, which binds to receptors on a cells. Without actually entering the cells, the two mating factors cause the cells to grow toward each other and also bring about other cellular changes. The result is the fusion, or mating, of two cells of opposite type. The new a/ cell contains all the genes of both original cells, a combination of genetic resources that provides advantages to the cell's descendants, which arise by subsequent cell divisions.

Question: fusion results in what?

Choices:
- A. the new a/ cell
- B. two cells of the opposite type

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen without fusion?

Choices:
- A. the new a/ cell would not be produced
- B. factors would not be secreted

Prompt: Given the context, pick the right choice that answers the question


Question: fusion results in a combination of genetic resources

Choices:
- A. False
- B. True

Prompt: Given the context, pick the right choice that answers the question


Question: What would happen if factors did not bind to receptors?

Choices:
- A. Cells would not secrete factor
- B. cells would not grow toward each other

Prompt: Given the context, pick the right choice that answers the question