AP BIOLOGY Scoring Guide

AP B TEST

1.

Figure 1. A cellular process

Which of the following best describes the cellular process illustrated in Figure 1 ?
(A) Sister chromatids separating during anaphase of mitosis
(B) Chromosomes lining up along the midline of the cell during mitosis
(C) Reducing the chromosome number during anaphaseof meiosis

(D) Chromatids failing to separate during meiosis

2. Within a forest ecosystem, there is a large amount of diversity among members of a warbler species. Of the
following stages of meiosis illustrated for a typical cell, which contributes most to diversity among the
warblers?

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(A)

(B)

(C)

(D)

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Pyruvate dehydrogenase is an enzyme that converts pyruvate to acetyl- . Acetyl- is further metabolized in the
Krebs cycle. A researcher measured the accumulation of acetyl- in a reaction containing pyruvate and pyruvate
dehydrogenase under several different conditions (Figure 1).

Figure 1. Accumulation of acetyl- under different conditions

3. Which of the following best describes the cellular location where pyruvate dehydrogenase is most likely active?
(A) The cytosol
(B) The lysosomes
(C) The nucleus
(D) The mitochondrial matrix

4. The maximum production rate of acetyl- under conditionis closest to which of the following?
(A)

(B)
(C)
(D)

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5. Pyruvate dehydrogenase deficiency is a genetic disease most commonly linked to a mutation in the -subunit of the
mitochondrial enzyme that causes the enzyme to cease functioning. As a result of the mutation, affected individuals
build up dangerous amounts of lactic acid. Which of the following best explains the buildup of lactic acid in
individuals with the mutation?
(A) Cells use lactic acid to shunt electrons from pyruvate to the electron transport chain in the mitochondria.
(B) Cells undergo glycolysis because there is a buildup of pyruvate in affected individuals.
Cells cannot transport pyruvate to the mitochondria in the absence of pyruvate dehydrogenase activity,
( so the pyruvate is broken down to lactic acid and ethanol.

(D) Cells undergo fermentation because pyruvate cannot be metabolized to proceed into the Krebs cycle.

6. In mammals, an increase in the concentration of sodium in the blood triggers the release of antidiuretic hormone
(ADH) from the pituitary gland. As the concentration of sodium in the blood returns to previous levels, the
release of ADH from the pituitary gland is reduced. Based on the information presented, which of the following
describes the most likely role of ADH in maintaining blood osmolarity?
(A) ADH promotes an increase in the movement of sodium into the bloodstream.
(C) ADH promotes an increase in the excretion of water from the body.
(B) ADH promotes an increase in the movement of water into the bloodstream.
(D) ADH promotes an increase in the secretion of additional ADH from the pituitary gland.

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7. The relative amount of in a cell at various stages of the cell cycle is shown in Figure 1 .

Figure 1. Amount of per cell during different stages of the cell cycle, relative to the beginning of the
stage

Which of the following best describes how the amount of in the cell changes during phase?
(A) The amount of doubles as the is replicated.
The amount of slightly increases as a result of new organelle synthesis.
The amount of does not change while the cell grows.

(D) The amount ofis halved as the cell divides into two daughter cells.

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8. Amylase is a protein that catalyzes the conversion of starch to simple sugars. Amylase activity in an aqueous
solution can be measured by using iodine as a starch indicator. A solution containing iodine and starch will have a
dark-blue color, whereas a solution containing iodine but no starch will have a light-brown color. The color
change of an iodine solution from dark blue to light brown can be used to measure the rate at which starch is
converted to simple sugars.

A student designs an experiment to investigate the effect of environmental on amylase function. The design of
the experiment is presented in Table 1.

Table 1. An experiment for investigating the effect of on amylase function

Test Tube Environmental Starch Added Amylase Added Iodine Added Pretreated by Boiling
5 Yes Yes Yes No
6 Yes Yes Yes No
7 No Yes Yes No
7 Yes No Yes No
7 Yes Yes Yes Yes
7 Yes Yes Yes No
8 Yes Yes Yes No
9 Yes Yes Yes No

Which of the following statements best justifies the inclusion of test tube as a control in the experiment?
It will provide a measurement of amylase activity at an acidic.
It will provide a measurement of amylase activity at a basic.

(C) It will show the color change that occurs in the absence of enzyme activity.

(D) It will show the color change that occurs in the absence of the amylase protein.

9. A scientist designed an experiment to test an artificial membrane that mimics the phospholipid bilayer of a cell.

The scientist built a tube that was divided by an artificial membrane and filled with distilled water. The scientist put
a known amount of a protein into the water on one side of the membrane. After some time, the scientist measured
the concentration of the protein on either side of the membrane but found that there had been no change.

Which of the following experimental changes would allow the scientist to observe transport of a solute across the
artificial membrane?
(A) Increase the solute concentration in the solution
(B) Use a small, nonpolar solute instead of a protein

(C) Increase the temperature of the solution

(D) Add artificial aquaporins to the membrane

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10. A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants.

Which of the following statements best supports the researcher’s claim?

Atmospheric carbon dioxide is produced by the burning of fossil fuels, which are formed from the
( remains of living organisms such as plants.
Atmospheric carbon dioxide is a byproduct of cellular respiration, which is a metabolic process that
( occurs in plants and other living organisms.
Atmospheric carbon dioxide typically enters plant leaves through stomata, which plants rely on for
( regulating gas exchange with the atmosphere.
Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and othe
(D)

11. The figures below illustrate the similarities between ATP synthesis in mitochondria and chloroplasts.

The figures can best assist in answering which of the following questions?
(A) Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?

(B) What are the sources of energy that drive mitochondrial and chloroplast electron transport systems?
What is the optimal temperature at which ATP synthase chemically converts ADP and a phosphate
( group into one molecule of ATP?
What is the evolutionary relationship between the ATP synthase in mitochondria and the ATP synthase
( in chloroplasts?

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12. Scientists compared the chemical structure of several molecules that various bacterial species use for quorum
sensing. Quorum sensing is an ability some bacteria have to detect the number of related cells nearby. The
chemical structure of some of these molecules found in certain species of bacteria are shown in Figure 1.

Figure 1. The chemical structure of several molecules used for quorum sensing in three species of bacteria

Which of the following research questions would best guide an investigation of the link between the structure of the
signaling molecules and the evolution of quorum sensing?
(A) Do these molecules require the same receptors in each bacteria species to generate a response?
(B) Did these species evolve from a common ancestor that used a similar signaling molecule?

Do these species all perform the same action when the concentration of the signaling molecules is high
( enough?
Did these species evolve from the same common ancestor that is still living today and uses the same
( receptors?

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13. A researcher claims that some bacteria contain factors that influence the function of a particular enzyme but other
bacteria do not. To test the claim experimentally, the researcher will grow two different bacterial strains in separate
liquid cultures and isolate the contents of the cells in each culture. The researcher will add different combinations
of cellular contents, substrate, and enzyme to test tubes containing a buffer solution adjusted to the optimal of
the enzyme and then measure the rate of product formation. The design of the researcher’s experiment is presented
in Table 1.

Table 1. An experiment for investigating the influence of bacterial factors on enzyme function

Test Source of Cellular Cellular Contents Substrate Enzyme

Tube Contents Added Added Added
1 Strain 1 No Yes Yes
2 Strain 1 Yes No Yes
3 Strain 1 Yes Yes No
4 Strain 1 Yes Yes Yes
5 Strain 2 No Yes Yes
6 Strain 2 Yes No Yes
7 Strain 2 Yes Yes No
8 Strain 2 Yes Yes Yes

Which of the following statements best justifies the inclusion of test tubes 3 and 7 in the experiment?
(A) They will show whether the isolated cellular contents have enzymatic activity.

(B)They will show whether environmental affects the function of the enzyme.
(C) They will show the rate of product formation in the absence of bacterial factors.
(D) They will show the rate of product formation in the absence of the substrate.

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To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria into
two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured the of
the cultures at -minute intervals as the bacteria metabolized the glucose into lactic acid. The data are shown in Table 1.

TABLE 1. AVERAGE CHANGE IN IN CONTROL AND TREATMENT GROUPS OVER A -MINUTE

PERIOD

Average of Control Average of Treatment

Time (min) ( ) ( )

14. Which of the following best describes the process by which the bacteria are breaking down the glucose to
produce lactic acid?
(A) The bacteria are breaking down sugars in the absence of oxygen.

(B)The bacteria are creating a gradient to synthesize more .

(C) The bacteria are using their mitochondria to break down glucose in the presence of oxygen.
(D) The bacteria are producing in the Krebs cycle that is then converted into lactic acid.

15. Which of the following was the dependent variable in the researcher’s experiment?
(A) Time
(B)

(C) Glucose concentration

(D) Lactic acid concentration

16. Which of the following graphs best represents the data in Table 1 ?

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(A)

(C)

(B)

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(D)

17. Based on the data in Table 1, which of the following is the earliest time point at which there is a
statistical difference in average between the control and treatment groups?
(A) minutes
(B) minutes
(C) minutes

(D)minutes

18. According to the data, which of the following best explains the results of the experiment?
The of the treatment culture was lower than the of the control because the chemical increased
(A)
the bacterial metabolic rate.
The of the treatment culture was higher than the of the control because the chemical
( denatured bacterial enzymes and decreased the metabolic rate.
(C) The chemical increased the metabolic rate of the bacteria because it lowered the .
(D) The chemical decreased the metabolic rate of the bacteria because it bound all available oxygen.

19. Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in
the initiation of a cancerous tumor?
A receptor mutation results in activation of a cell-division pathway in the absence of the appropriate
( ligand.
(B) A mutation results in the loss of the ability to produce a tumor-suppressor protein.
(C) A defect in a cell-cycle checkpoint prevents a cell from entering the S phase.

At the anaphase checkpoint, separation of chromatids occurs without all centromeres being attached to
( kinetochore microtubules from both poles.

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20. Researchers performed an experiment to determine the effect of certain genetic mutations on mitosis in tropical
fruit fly embryos. They determined the percentage of cells in each of four phases of mitosis as shown in Figure 1.

Figure 1. Percent of cells in phases of mitosis

Which of the following patterns is shown by the data?

(A) Mutant 1 cells are more similar to mutant 3 cells than to wild-type cells.
(B) In wild-type cells, the percent of cells in anaphase is twice the amount of those in telophase
(C) In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis.

(D) The percent of mutant 2 cells in anaphase is higher than that of mutant 1 cells.

21. What is the expected percent change in the content of a typical eukaryotic cell as it progresses through
the cell cycle from the start of the phase to the end of the phase?
(A)
(B)
(C)

(D)

22. Cholesterol is an important component of animal cell membranes. Cholesterol molecules are often delivered to
body cells by the blood, which transports the molecules in the form of cholesterol-protein complexes. The
complexes must be moved into the body cells before the cholesterol molecules can be incorporated into the
phospholipid bilayers of cell membranes.

Based on the information presented, which of the following is the most likely explanation for a buildup of
cholesterol molecules in the blood of an animal?

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(A) The animal’s body cells are defective in exocytosis.

(B) The animal’s body cells are defective in endocytosis.

(C) The animal’s body cells are defective in cholesterol synthesis.

(D) The animal’s body cells are defective in phospholipid synthesis.

23. Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of
cell division.

Figure 1. Number of chromosomes in a human cell at different stages of cell division

Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure
1?
replication occurs between metaphase and anaphase, doubling the number of chromosomes.
(A) Between telophase and cytokinesis, the cell divides in two, with each cell receiving half of the
replicated chromosomes.
New chromosomes formed during prophase are doubled during anaphase and are recombined before
( cytokinesis.
Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase,
(C) the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate

At anaphase a cell contains two identical copies of each chromosome, but following telophase, one of
( the copies is broken down into nucleotides.

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24. The diploid number of chromosomes in the cell of a domesticated dog is . Which of the following options
includes the correct number of chromosomes in a cell after each cellular process ( checkpoint, meiosis, and
fertilization, respectively)?

After After After

(A) Checkpoint Meiosis Fertilization

After After After

(B) Checkpoint Meiosis Fertilization

After After After

(C) Checkpoint Meiosis Fertilization

After After After

(D) Checkpoint Meiosis Fertilization

25. If of the nucleotides in a single-stranded molecule are adenine, then what percent are expected to
be thymine?

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(A)

(B)
(C)
(D)

26. Which of the following describes the most likely location of cholesterol in an animal cell?
(A) Embedded in the plasma membrane

(B) Dissolved in the cytosol

(C) Suspended in the stroma of the chloroplast
(D) Bound to free ribosomes

27. A researcher designs an experiment to investigate the effect of environmental temperature on the function of an
enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an
aqueous buffer solution and then measure the amount of product formed over 20 minutes.

Which of the following must remain the same for all trials of this experiment?
(A) The initial concentration of the substrate

(B) The final concentration of the product

(C) The three-dimensional structure of the enzyme
(D) The temperature of the aqueous buffer solution

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28.

Figure 1. Model of crossing over between homologous chromosomes, indicating crossing over rate of selected loci.

During prophase replicated homologous chromosomes pair up and undergo synapsis. What testable question
is generated regarding synapsis and genetic variability by Figure 1 ?
(A) Is the distance between two gene loci related to crossover rate?

(B) Does crossing over occur more often in some chromosomes than in others?
(C) Is crossing over inhibited by methylation?
(D) Is crossing over promoted by methylation?

29. Scientists have found that methylation suppresses crossing-over in the fungus Ascobolus immersus. Which of
the following questions is most appropriately raised by this specific observation?
(A) Is the level of genetic variation in the gametes related to the amount ofmethylation observed?

(B) Without crossing-over, will gametes be viable and be able to produce zygotes?
(C) Does methylation result in shorter chromosomes?
(D) Is this species of fungus a diploid organism?

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30.

Figure 1. Diagram of the electron transport chain and synthase in the membrane of mitochondria

On average, more can be produced from an molecule than can be produced from a molecule of
. Based on Figure 1, which of the following best explains the difference in production between these
two molecules?
contributes more electrons to the electron transport chain than does and therefore
( provides more energy to pump protons.
The electrons of whereas those
are transferred
of through three complexes of the electron transport chain are transferred throug
(B)

(C) contributes more protons to the mitochondrial matrix, which decreases the proton gradient.
The protons contributed by are combined with to make water and are not pumped across
( the membrane.

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31. Figure 1 represents a nucleic acid fragment that is made up of four nucleotides linked together in a chain.

Figure 1. Nucleic acid fragment

Which of the following characteristics of Figure 1 best shows that the fragment is and not ?
(A) Thetoorientation of the nucleotide chain
(B) The identity of each nitrogenous base

(C) The charges on the phosphate groups

(D) The type of bond linking the nucleotides together

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32.

Figure 1. Nucleic acid segments

and are nucleic acids that can store biological information based on the sequence of their nucleotide
monomers. Figure 1 shows a short segment of each of the two types of nucleic acids.

Which of the following best describes a structural difference between and ?

contains four types of nitrogenous bases, whereas contains only two types of nitrogenous
(A)
bases.
(B) The backbone ofcontains deoxyribose, whereas the backbone ofcontains ribose.

A molecule is composed of two parallel strands with the same to directionality, whereas an
(C)
molecule is composed of only onetostrand.
(D) Phosphate groups provide rigidity to , but is flexible and contains no phosphate groups.

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33. Newborn babies and hibernating animals contain a large amount of brown adipose (fat) tissue ( ). Certain
proteins in the cells increase the permeability of the inner mitochondrial membrane to protons, disrupting the
proton gradient.

Which of the following best predicts the effect of disrupting the proton gradient in ?
(A) The of the matrix will increase, allowing the production of more per gram of substrate.
(B) The of the intermembrane space will decrease, allowing a steeper proton gradient to form.
Electron transport and oxidative phosphorylation will be decoupled, generating more heat but less
(C)
.
(D) The number of protons available to pass through synthase will increase, resulting in more .

34. The drug -fluorouracil inhibits thymine production in eukaryotic cells. Which of the following cell cycle stages will be most
(A) The first growth phase ()

(B) Synthesis of DNA phase ( )

(C)Preparation for mitosis ()

(D) Cytokinesis

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Melanocytes are skin cells that can become cancerous and develop into a cancer known as melanoma. Some
cancerous melanocytes have developed resistance to the drugs currently used to treat melanoma. As a result,
researchers are investigating the effects of a new compound (drug ) on four different melanoma
cell lines. Researchers analyzed cell survival in two cell lines (Figure 1) and oxygen consumption in the presence of
drug in all four cell lines (Figure 2). Figure 3 shows the proposed
mechanism by which drug affects cells.

Figure 1. Percent survival of normal melanocytes and cancerous melanocyte (melanoma) lines and after treatment
with different concentrations of drug

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Figure 2. Oxygen consumption per cell in four melanoma lines after treatment with either solvent alone or
solvent containing drug . Error bars represent .

Figure 3. Pathway leading to cell survival, growth, and proliferation and the likely effect of drug

35. Which of the following best describes the data in Figure 1 ?

(A) As the concentration of drug increases, there is an increase in melanoma cell survival.
(C) At a concentration below μ , drug increases survival in all melanoma cell lines.
(B) At a concentration above μ , drug reduces melanoma cell survival.
(D) At a concentration of μ , drug has a greater effect on melanoma line than on melanoma line .

36. Based on Figure 2, which of the following best supports the claim that drug inhibits oxygen consumption?
(A) In the absence of drug , melanoma lines and consume similar amounts of oxygen.
In the presence of drug , melanoma line consumes statistically more oxygen per cell than
( does melanoma line .
Melanoma lineconsumes statistically less oxygen per cell in the presence of drug presence
thanofit the
doessolvent
in the alone.
(C)

Melanoma line in the presence of drug consumes statistically less oxygen than does melanoma line
( in the absence of drug .

37. Based on the information presented, which of the following best explains why the researchers measured
oxygen consumption as an indicator of the effectiveness of drug ?
(A) Oxygen provides the source of electrons for cellular respiration and is necessary for energy production.
(B) Oxygen consumption increases the mutation rate and causes cells to become cancerous.
(C) Oxygen activates apoptosis, which results in the death of melanoma cells.

(D) Oxygen accepts electrons in oxidative phosphorylation, a process necessary for melanoma cell survival.

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38.

Figure 1. A model of epinephrine signaling

Two types of cells, alpha and beta cells, produce signaling molecules that affect blood sugar levels in opposite ways
(Figure 1). Epinephrine is a chemical, often released during periods of exercise, that ultimately causes an increase
in blood sugar levels in the body.

Based on Figure 1, which of the following best explains how exercise causes blood glucose levels to rise?

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Epinephrine inhibits alpha cells, causing the release of glucagon, and activates beta cells, blocking the
( release of insulin.
Epinephrine activates alpha cells, blocking the release of glucagon, and inhibits beta cells, causing the
( release of insulin.
Epinephrine activates alpha cells, causing the release of glucagon, and inhibits beta cells, blocking the release of insuli
(C)

Epinephrine inhibits alpha cells, blocking the release of glucagon, and activates beta cells, causing the
( release of insulin.

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39. Scientists investigated the effect of oxygen levels on the net rate of carbon fixation in two types of plants. The
plants were grown in either well-watered soil (control) or dry soil and then exposed to either or .
The net rate of fixation for both types of plants was measured. Data are shown in Figure and Figure .

Figure 1. Net rate of fixation in two types

of plants grown in wet (control) or dry soil
at

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Figure 2. Net rate of fixation in two types

of plants grown in wet (control) or dry soil at

Which of the following statements about the rate of fixation in the two types of plants is supported by the
data shown in the figures?
At , plant type has a higher rate of fixation than plant type does in the dry soil but not
((A) inAtthe control, soil.
plant type has a lower rate of fixation than plant type does in both types of soil.
Plant types and have a statistically different rate of fixation in both soil types at both oxygen
( levels.
(D) The rate of fixation is the same in both types of plants in the control soil at both oxygen levels.

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40. Scientists were interested in testing the effects of rotenone, a broad-spectrum pesticide, on a cell culture. Cell
culture was used as a control, while culture was treated with rotenone. After a period of time, the scientists
measured the concentration of several metabolites in the mitochondria of cells in both cultures. Their results are
shown in the table below.

Metabolites Concentration in Culture μ Concentration in Culture μ

Pyruvate

Based on the data in the table, which of the following best explains the effects of rotenone on cellular respiration?
(A) Rotenone acts as an inhibitor of the enzymes in the Krebs cycle.
, produced during glycolysis, is not able to enter the mitochondria because transport proteins are
( blocked from entering.
Treated cells are not able to break down chain arebecause
inhibited.
certain enzymes of the electron transport
(C)

(D) Rotenone acts as an allosteric inhibitor of glycolytic enzymes, thus inhibiting cellular respiration.

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Certain chemicals, including sodium fluoride ( ), are capable of inhibiting specific steps of glycolysis. Figure 1 shows
the steps of the glycolysis pathway, indicating where various macromolecules enter the pathway as well as the specific
reaction inhibited by .

Figure 1. Key steps in the metabolic pathway of glucose

41. Based on Figure 1, the net number of molecules produced during glycolysis from the metabolism of a
single glucose molecule is closest to which of the following?
(A)
(B)

(C)
(D)

42. Tarui disease is an inherited disorder that is caused by mutations in , the gene that encodes a subunit of
phosphofructokinase, an enzyme in the glycolysis pathway. Individuals with Tarui disease produce little or no
functional phosphofructokinase in skeletal muscle cells. Based on Figure 1, which of the following best explains
why a low carbohydrate diet is recommended for those with Tarui disease?

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Carbohydrates are capable of undergoing lactic acid fermentation, and amino acids and fatty acids are
( not.
(B) Carbohydrate metabolism requires all the reactions of glycolysis, and amino acids and fatty acids do not.

Carbohydrates cannot be used to synthesize important metabolic enzymes like amino acids and fatty
( acids can be.
(D) Carbohydrates cannot be stored, while amino acids and fatty acids can be.

43. Researchers have identified a molecule produced by Ecteinascidia turbinata, a marine invertebrate, from which
the drug trabectedin is produced. Soft-tissue tumors treated with trabectedin rapidly decrease in size. In a
preliminary study, healthy cells and tumor cells sampled from skin cancer patients treated with trabectedin were
collected, and several characteristics of the cells were observed. The observed results of the study are shown in the
table.

Characteristic Healthy Cell Tumor Cell

(in picograms) Nuclear envelope Nucleolus
Cyclin level
General appearance Thinning Absent High
Present Present Low
Round, firm Shrunken

Which of the following best explains the most likely method by which this antitumor drug works?
(A) Trabectedin increases the production of cyclin proteins that signal the cancer cells to enter prophase.
Trabectedin interferes with the plasma membrane, causing it to break down and expose the to
( damage.
Trabectedin interferes with the duplication of from passing
duringthecheckpoint.
interphase and thus prevents cancer cells
(C)

Trabectedin interferes with the regulations of cyclin proteins, causing their levels to increase and
( creating errors in .

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44.

The diagram above shows a developing worm embryo at the four-cell stage. Experiments have shown that when
cell 3 divides, the anterior daughter cell gives rise to muscle and gonads and the posterior daughter cell gives rise to
the intestine. However, if the cells of the embryo are separated from one another early during the four-cell stage, no
intestine will form. Other experiments have shown that if cell 3 and cell 4 are recombined after the initial
separation, the posterior daughter cell of cell 3 will once again give rise to normal intestine. Which of the following
is the most plausible explanation for these findings?
(A) A cell surface protein on cell 4 signals cell 3 to induce formation of the worm’s intestine.

The plasma membrane of cell 4 interacts with the plasma membrane of the posterior portion of cell 3,
( causing invaginations that become microvilli.
(C) Cell 3 passes an electrical signal to cell 4, which induces differentiation in cell 4.
(D) Cell 4 transfers genetic material to cell 3, which directs the development of intestinal cells.

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The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway
is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine
signaling pathway is represented in Figure 1.

Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells

45.A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following

(A) Epinephrine is a signaling molecule that binds to a transmembrane protein.

(B) The G protein in the epinephrine signaling pathway consists of three different subunits.
(C)
Phosphorylase kinase catalyzes the hydrolysis of .
(D) Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phosphate.

46. Ethylene causes fruits to ripen. In a signaling pathway, receptors activate transcription factors, which
ultimately leads to ripening.

Which of the following best supports the claim that ethylene initiates the signal transduction pathway that leads to
ripening of fruit?

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(A) Ethylene is a simple gaseous molecule, which makes it easily detected by receptors.
(B) Fruit will ripen in closed containers without exposure to air.
(C) Ethylene synthesis is under both positive and negative feedback regulation.
(D) Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

47.

The brain coordinates the circulatory and respiratory systems of the human body. The control of breathing, for
example, involves neural pathways among the structures represented in the figure above. One important stimulus in
the control of breathing is an increase in blood CO 2 concentration, which is detected as a decrease in blood pH.
Which of the following best describes the physiological response to an overall increase in cellular respiration in the
body?
In response to depleted blood CO2 levels, the pH sensors send signals directly to the rib muscles,
(A) resulting in an increase in the rate of CO2 uptake by the lungs and a decrease in CO2 utilization by the
brain.
In response to low blood pH, the pH sensors send a signal to the brain, which then sends a signal to the diaphragm, r
(B)

In response to high blood pH, the pH sensors send a signal directly to the lungs, resulting in a slower
(C) rate of breathing, and the lungs send a signal back to the heart once CO availability has been restored.
2
In response to an increased rate of breathing, the rib muscles send a signal to the brain, which then sends
( a signal to the heart, resulting in a decrease in heart activity and slower flow of blood through the body.

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48. Gelatin is a protein that is derived from collagen which is found in the bones, skin, and connective tissue of animals.
To investigate the ability of various enzymes to digest gelatin, a group of students set up an assay involving camera
film. Camera film contains gelatin and appears black when exposed to light but turns clear as the gelatin gets
broken down. The students incubated pieces of exposed camera film in test tubes, each containing one of three
different enzyme solutions (trypsin, lipase, or amylase) as indicated in Figure 1. The students recorded the time it
took for the enzymes to digest the gelatin in each test tube, turning the film from black to clear.

Figure 1. Diagram of experimental setup.

Which of the following would be the most appropriate control for this experiment?
(A) A test tube containing no camera film
(B) A test tube containing only a piece of exposed camera film
(C) A test tube containing a piece of exposed camera film submerged in water

(D) A test tube containing a piece of exposed camera film and all three enzyme solutions

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A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was
wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant
from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both
dishes. The dishes were examined after 7 days and the opaque cover was permanently removed from dish A. Both dishes
were returned to the light and examined again at 14 days. The following data were obtained.

49.According to the results of this experiment, germination of tobacco seeds during the first week is
(A) increased by exposure to light

unaffected by light intensity

prevented by paper towels
accelerated in green-leaved seedlings

Additional observations were made on day 21, and no yellow-leaved seedlings were found alive in either dish. This is most likely b
yellow-leaved seedlings were unable to absorb water from the paper towels
taller green-leaved seedlings blocked the light and prevented photosynthesis

(C) yellow-leaved seedlings were unable to convert light energy to chemical energy

(D) a higher rate of respiration in yellow-leaved seedlings depleted their stored nutrients

51. Glycogen synthetase kinase 3 beta is a protein kinase that has been implicated in many types of cancer.
Depending on the cell type, the gene for glycogen synthetase kinase 3 beta can act either as an
oncogene or as a tumor suppressor.

Which of the following best predicts how mutations can lead to the development of cancer?

(A) Cells with inactive fail to trigger apoptosis.

(B) Cells with inactive fail to proceed past the checkpoint.
(C) Cells with overactive are more likely to repair damage.
(D) Cells with overactive have longer cell cycles.

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Dichlorophenolindophenol ( ) is a chemical dye. When is chemically reduced, it changes color from

blue to clear. can be used as an electron acceptor in experiments that measure the rate of electron transport
through the electron transport chain. A student performed an experiment to study the effects of a chemical, , on
photosynthesis.

The student prepared four tubes with a liquid buffer and chloroplasts that had been extracted from spinach leaves. The
student then added to three of the tubes and added to one of them. Additionally, tube was wrapped in
tin foil. The contents of each tube are shown in the table. The student then incubated each tube for minutes and
measured the absorbance ( ) of each solution at five-minute intervals. The absorbance readings of each solution are
shown in Figure 1.

Tube : Buffer and water

Tube : , buffer, and water
Tube : , buffer, and water (wrapped in foil)
Tube : , buffer, and

Figure 1. Absorbance readings of four prepared tubes with various solutions over a -minute period.

52. Which of the following claims is best supported by the experimental results?

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(A) Light is required for the electron transport chain to transfer electrons.

Water, not carbon dioxide, is the source of electrons used in the light-dependent reaction of
( photosynthesis.
(C) Carbon dioxide is the source of carbon used by green plants to build carbohydrates.
provides a significant source of electrons to the electron transport chain of the light reaction in
(D)
the absence of light.

53.Which of the following best justifies the use of tubeas a control treatment?
It was a negative control for the accuracy of the spectrophotometer, ensuring that an accurate reading for treatment cuv
(A)
It was a negative control for the chemical stability of the chlorophyll suspension, ensuring that changes in absorbance
(B)

(C)It was a positive control for the change incolor associated with changes in light intensity.
(D) It was a positive control for measuring the effect ofon the reaction.

54. A model showing two possible arrangements of chromosomes during meiosis is shown in Figure 1.

Figure 1. Two possible arrangements of chromosomes during meiosis

Which of the following questions about genetic diversity could most appropriately be answered by analysis of the
model in Figure 1 ?
(A) Does crossing-over generate more genetic diversity than the fusion of gametes does?
(B) Does methylation prevent independent assortment during metaphase ?
How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?
(C)

(D) Do daughter cells that are not genetically identical to parent cells produce viable zygotes?

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Figure 1. Pathway activated by insulin binding to the insulin receptor

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Figure 2: Blood insulin levels in normal mice and mutant mice after exposure to glucose

Hormones are chemical signals that are released by cells in one part of the body that travel through the bloodstream to
signal cells in another part of the body. Insulin is a hormone that is released by the pancreas that induces the uptake of
glucose molecules from the bloodstream into cells. In this way, insulin lowers the overall blood glucose levels of the
body. Osteoblasts and osteoclasts are two types of bone cells that play a role in regulating blood glucose levels (Figure 1).

Binding of insulin to the insulin receptor on osteoblasts activates a signaling pathway that results in osteoblasts releasing a
molecule, , that binds to neighboring osteoclasts. In response, the osteoclasts release protons ( ) and create an
area of lower outside the cell. This low activates osteocalcin, a protein secreted in an inactive form by osteoblasts.

The gene encodes a protein that alters the structure of the insulin receptor on osteoblasts and interferes with the
binding of insulin to the receptor. A researcher created a group of osteoblasts with an mutation that prevented the
production of a functional product (mutant). The researcher then exposed the mutant strain and a normal strain
that expresses to glucose and compared the levels of insulin in the blood near the osteoblasts (Figure 2).

55. Based on the information provided, which of the following best justifies the claim that osteocalcin is a hormone?
(A) The phosphorylation of the insulin receptor causes a response in osteoblast bone cells.
The osteoblasts in the bone secrete osteocalcin, which causes cells in the pancreas to change their activity.
(B)

(C)The change in expression of changes the insulin receptor activity of the osteoblast.
(D) The activation of the osteocalcin by a bone cell is dependent.

56. Which of the following claims is most consistent with the data shown in Figure 2 ?
(A)expression is necessary to prevent the overproduction of insulin.

(B) protein does not regulate blood-sugar levels in normal mice.

(C) Normal mice require a higher blood concentration of insulin than mutant mice do.
(D) Mutant mice have a cyclical pattern of insulin secretion.

57. Which of the following was a positive control in the experiment?

(A) Minutes after glucose injection
(B) Blood insulin
(C) Mutant strain

(D) Normal strain

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58. In an experiment, a scientist isolates mitochondria from living cells and suspends them in two different buffered
solutions. One solution is maintained at pH 4, while the other solution is maintained at pH 9. The scientist finds
that mitochondria in the solution at pH 4 continue to produce ATP but those in the pH 9 solution do not.

The results of the experiment can be used as evidence in support of which of the following scientific claims about
mitochondrial activity?
(A) Mitochondria in a cell-free environment are unable to convert thermal energy into ATP.
(B) The electron transport chain pumps electrons from the cytosol to the mitochondrial matrix.
ATP production in mitochondria requires a hydrogen ion gradient that favors movement of protons into the mitochond
(C)

ATP synthase molecules change their orientation in relation to the proton gradient across the
( mitochondrial membrane.

59. In chloroplasts, is synthesized from plus inorganic phosphate in a reaction catalyzed by

synthase molecules that are embedded in the thylakoid membrane.

Which of the following statements provides evidence to support the claim that no will be synthesized in the
absence of a proton gradient across the thylakoid membrane?
Blocking electron flow from one carrier to the next in the electron transport chains blocks formation of a
( proton gradient in the thylakoid.
Increasing the proton concentration difference across the thylakoid membrane is not associated with a
( parallel increase in the rate of synthesis.
No is synthesized when channel proteins that allow the free passage of protons are inserted into
(C)
the thylakoid membrane.
No is synthesized while the Calvin cycle is synthesizing carbohydrates and using at a high
andrate.
(D)

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60.

Which of the following questions will best direct an investigation of the mechanism of ATP synthase?
(A) What is the source of the inorganic phosphate that is used to generate ATP from ADP?
(B) Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient?

Can ATP synthase use the energy released by phosphorylation of ADP to pump protons against a
( concentration gradient?
(D) Can oxidative phosphorylation be uncoupled from the electron transport chain?

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61. Table 1 shows the stage and number of cells and chromosomes per cell at the end of the stage in a
organism.

Table 1. Cell and chromosome count during selected phases of meiosis

Stage Number of Cells Number of Chromosomes per Cell

Prophase 1 24
Metaphase 1 24
Anaphase 1 24
Telophase 1 24
Beginning of Prophase 2 12

Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis
?
Each daughter cell contains 12 chromatids. Each chromatid is one of two from a single chromosome
( with the other one of the pair found in the other daughter cell.
Each daughter cell contains 12 chromosomes, each composed of two chromatids. Since the
(B) chromosomes were randomly divided, one daughter cell may contain both of a pair of
homologous chromosomes, while the other cell contains both of another pair of homologous
chromosomes.
Each daughter cell contains 12 chromosomes, each composed of two chromatids. Each chromosome is
(C) one of a pair of homologous chromosomes from the parent cell, with the other homologue found in the other daughter ce

Each daughter cell contains 24 separate chromatids. Since every two chromatids were originally joined,
(D) forming one homologous chromosome, the number of chromatids is divided by two to determine the
number of chromosomes.

62. Both mitosis and meiosis begin with a parent cell that is diploid. Which of the following best describes how
mitosis and meiosis result in daughter cells with different numbers of chromosomes?
In mitosis, the chromosomes consist of a single chromatid, which is passed to two haploid daughter
(A) cells. In meiosis, the chromosomes consist of two chromatids during the first round of division and
one chromatid during the second round of division, resulting in two haploid daughter cells.
In mitosis, synapsis of homologous chromosomes results in four haploid daughter cells after one
(B) division. In meiosis, synapsis of homologous chromosomes occurs during the second division
and results in four diploid daughter cells.
Mitosis produces one identical daughter cell after one round of division. Meiosis has two rounds of
(C) division and doubles the number of chromosomes in the second round of division, producing
four diploid cells.
Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daugh
(D)

63. Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?

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(A) An increase in blood pH due to the accumulation of lactic acid

(B) No ATP production due to the absence of substrate-level phosphorylation
(C) A buildup of lactic acid in the muscle tissue due to fermentation

(D) A decrease in the oxidation of fatty acids due to a shortage of ATP

64. Vertebrate immune responses involve communication over short and long distances. Which of the following
statements best helps explain how cell surface proteins, such as proteins and T cell receptors, mediate cell
communication over short distances?
(A) The proteins receive electrical signals from nerve cells.
(B) The proteins leave the cell and travel in the bloodstream to other cells.
(C) The proteins interact directly with proteins on the surfaces of other cells.

(D) The proteins bind to molecules secreted by cells located in other parts of the body.

65.

The figure above shows an organelle typically found in eukaryotic cells. Which of the following best describes the
function of the double membrane system of this organelle?
The outer membrane allows the transport of all molecules into the intermembrane space, while the inner
( membrane serves as the regulatory boundary.
The inner membrane has specialized proteins that create a hydrogen ion concentration gradient between the intermemb
(B)

The outer membrane contains transport proteins that establish a sodium ion concentration gradient used
(C) for ATP production, while the inner membrane contains transport proteins that establish a hydrogen
ion concentration gradient used for glucose production.
The toxins and wastes entering a cell cross the outer membrane and are detoxified by digestive enzymes
( stored within the intermembrane space.

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66. Which of the following best describes the role of mitosis in the cell cycle?
(A) Distributing replicated chromosomes to daughter nuclei

(B) Dividing the cytoplasm to form four gametes

(C) Producing organelles and replicating chromosomes
(D) Exchanging genetic material between homologous chromosomes

67.

Based on the model of eukaryotic cell cycle regulation shown in the figure, which of the following best describes
the effect of a drug that blocks the production of the mitotic cyclin?
(A) The cell cycle would proceed uncontrollably, and the cell would become cancerous.
(B) The G1 cyclin would functionally replace mitotic cyclin, and the cell would continue dividing normally.
(C) DNA synthesis would be prevented, and the cell would stop dividing.
(D) The cell would be prevented from entering mitosis, and the cell would stop dividing.

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68.

Figure 1. Diagram of the cell cycle with key checkpoints

Which of the following describes a mutation that would lead to an increase in the frequency of nondisjunction?
A mutation affecting checkpointproteins that forces cells to enter
A mutation affecting checkpointproteins that allows cells to divide with damage
(C) A mutation affecting checkpointproteins that prevents attachment of spindle fibers

(D) A mutation affecting checkpointproteins that prevents duplication of the chromosomes

69. Cancer cells behave differently than normal body cells. For example, they ignore signals that tell them to stop
dividing.

Which of the following conditions will most likely cause a normal body cell to become a cancer cell?
(A) The environment already contains cancer cells.
(B) The environment has an abundance of nutrients.
(C) The environment lacks signals that would otherwise tell the cell to stop dividing.
(D) The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins.

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70. Notch is a receptor protein displayed on the surface of certain cells in developing fruit fly embryos. Notch’s ligand
is a membrane-bound protein called Delta that is displayed on the surface of adjacent cells. When Notch is
activated by its ligand, the intracellular tail of the Notch protein becomes separated from the rest of the protein.
This allows the intracellular tail to move to the cell’s nucleus and alter the expression of specific genes.

Which of the following statements best explains Delta’s role in regulating cell communication through the Notch
signaling pathway?
(A) Delta transmits a chemical signal to all the cells of a developing embryo.
(B) Delta allows the cells of a developing embryo to communicate without making direct contact.
(C) Delta restricts cell communication to short distances within a developing embryo.

(D) Delta determines which cells in a developing embryo express the gene that encodes the Notch protein.

71.

Which of the following conclusions is most clearly supported by the representations of nucleic acid and nucleic
acid ?

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(A) Nucleic acid contains only purines, whereas nucleic acid contains only pyrimidines.
Nucleic acid contains the sugar ribose, whereas nucleic acid contains the sugar deoxyribose.
Nucleic acid contains positively charged phosphate groups, whereas nucleic acid does not.
(D) Nucleic acidcontains adenine-thymine base pairs, whereas nucleic aciddoes not.

72. Which of the following statements best explains the processes of passive and active transport?
Passive transport is the net movement of substances down a concentration gradient that requires
(A) metabolic energy. Active transport is the movement of substances up a concentration gradient that
does not require energy.
Passive transport is the net movement of substances down a concentration gradient that does not require
(B) metabolic energy. Active transport is the movement of substances up a concentration gradient that requires energy.

Passive transport is the net movement of substances up a concentration gradient that requires metabolic
(C) energy. Active transport is the movement of substances down a concentration gradient that does
not require metabolic energy.
Passive transport is the net movement of substances up a concentration gradient that does not require
(D) metabolic energy. Active transport is the movement of substances down a concentration gradient
that requires energy.

73. A researcher claims that different enzymes exhibit maximal function over different ranges. To test the claim,
the researcher carries out an experiment that includes three different enzymes: pepsin, salivary amylase, and
arginase. The results of the experiment are represented in Figure 1.

Figure 1. The effect of on three different enzymes

Which of the following actions will provide the most appropriate negative control for the experiment?
(A) Repeating the experiment with a fourth enzyme
(B) Repeating the experiment at several different temperatures
(C) Repeating the experiment with denatured enzymes

(D) Repeating the experiment using several different methods for measuring

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74.

Which of the following best describes the numbered areas?

(A) Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.

(B) Area 2 is polar, since water has been excluded from this area of the membrane.
(C) Areas 1 and 3 are hydrophilic, since membrane molecules formed covalent bonds with water.
(D) Area 2 is nonpolar, since hydrogen bonds between the adjacent lipids hold the membrane together.

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75. The model below shows the structure of a portion of a plasma membrane in an animal cell.

Which statement best explains the orientation of the phospholipid molecules in this model?
The nonpolar portions of the phospholipid molecules are attracted to the internal and external
( environments.
The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external env
(B)

The embedded proteins attract the fatty acid tails of the phospholipids, so the tails point away from the
( internal and external aqueous environments.
The fatty acid tails of the phospholipid molecules are hydrophilic and are repelled by the internal and
( external aqueous environments.

76. A scientist claims that Elysia chlorotica, a species of sea slug, is capable of photosynthesis.

Which of the following observations provides the best evidence to support the claim?
(A) Elysia chlorotica will die if not exposed to light.
(B) Elysia chlorotica grows when exposed to light in the absence of other food sources.

(C) Elysia chlorotica grows faster when exposed to light than when placed in the dark.
(D) Elysia chlorotica grows in the dark when food sources are available.

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77. In an experiment, cells were isolated from an aquatic plant and suspended in pond water, a sucrose sugar solution,
or distilled water. All of the cells were then viewed under a microscope. Compared with the cell in the pond
water, the cell in the sugar solution appeared shriveled, and the cell in the distilled water appeared inflated. The
results of the experiment are represented in Figure 1.

Figure 1. The results of an experiment using aquatic plant cells

Which of the following statements best explains the observations represented in Figure 1 ?
There was a net movement of sucrose out of the cell suspended in the sugar solution and a net
( movement of sucrose into the cell suspended in the distilled water.
There was a net movement of sucrose into the cell suspended in the sugar solution and a net movement
( of sucrose out of the cell suspended in the distilled water.
There was a net movement of water out of the cell suspended in the sugar solution and a net movement of water into th
(C)

There was a net movement of water into the cell suspended in the sugar solution and a net movement
( of water out of the cell suspended in the distilled water.

78. Which of the following best explains how small molecules move between adjacent cells in a plant shoot?
(A) The molecules are actively transported by motor proteins along the cytoskeleton.
(B) The molecules pass freely through plasmodesmata, which are cytoplasmic strands connecting two cells.

(C) The molecules are swept along in the extracellular fluid by cilia projecting from cell membranes.
(D) The molecules bind reversibly to receptors on the cell membranes of xylem.

79. To test the hypothesis that a particular plant synthesizes storage lipids by using glyceraldehyde 3-phosphate (G3P)
from photosynthesis, a researcher plans to use radiolabeled precursors to track the molecules through the
biosynthetic pathway. Which of the following radiolabeled precursors is most appropriate for the researcher to
use?

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(A) 15N-labeled N2, because atmospheric nitrogen is fixed to amino acids by photosynthesis
(B) 14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis

(C) 35S-labeled methionine, because amino acids are incorporated into lipids during photosynthesis
(D) 32P-labeled phosphate, because lipids are stored in plants as phospholipids

80. In flowering plants, plasmodesmata are narrow channels through cell walls that connect the cytoplasms of
adjacent cells. An explanation of how plant cells communicate across cell walls will most likely refer to the
diffusion through plasmodesmata of which of the following?
(A) Membrane-bound organelles
(B) Condensed, duplicated chromosomes
(C) Branched polysaccharides
(D) Small, water-soluble molecules

81. A researcher is conducting an experiment in which cells in different phases of the cell cycle are fused together.
The researcher then records what happens to the nuclei of the resulting cell (Table 1).

TABLE 1. COMBINATIONS OF CELLS THAT WERE FUSED AND THE PHASE OF NUCLEI IN THE
RESULTING CELL

Phase of Cell Phase of Cell Phase of Nuclei in Resulting Cell

phase phase phase phase Two -phase nuclei

One -phase nucleus and one -phase nucleus

One-phase nucleus and one

phase phase

-phase nucleus

Interphase phase Two-phase nuclei

Which of the following research questions is best addressed by the experiment?

(A) How do chemical messengers affect a cell’s transition between the phases of the cell cycle?

(B) How does the number of chromosomes affect when a cell transitions to the next phase of the cell cycle?
(C) How does the amount of genetic information change throughout the cell cycle?
(D) How does the checkpoint at serve to prevent the transmission of mutations?

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82. The chemical reaction for photosynthesis is

6 CO2 + 12 H2O + light energy → C6H12O6 + 6 O2 + 6 H2O

If the input water is labeled with a radioactive isotope of oxygen, 18O, then the oxygen gas released as the reaction
proceeds is also labeled with 18O. Which of the following is the most likely explanation?
During the light reactions of photosynthesis, water is split, the hydrogen atoms combine with the CO2,
( and oxygen gas is released.
During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released
(B)

(C) During the Calvin cycle, water is split, regenerating NADPH from NADP+, and oxygen gas is released.
During the Calvin cycle, water is split, the hydrogen atoms are added to intermediates of sugar
( synthesis, and oxygen gas is released.

An experiment to measure the rate of respiration in crickets and mice at 10 oC and 25oC was performed using a
respirometer, an apparatus that measures changes in gas volume. Respiration was measured in mL of O2 consumed per
gram of organism over several five-minute trials and the following data were obtained.

83. During aerobic cellular respiration, oxygen gas is consumed at the same rate as carbon dioxide gas is produced.
In order to provide accurate volumetric measurements of oxygen gas consumption, the experimental setup should
include which of the following?
(A) A substance that removes carbon dioxide gas

(B) A plant to produce oxygen

(C) A glucose reserve
(D) A valve to release excess water

84. According to the data, the mice at 10oC demonstrated greater oxygen consumption per gram of tissue than did
the mice at 25oC. This is most likely explained by which of the following statements?

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(A) The mice at 10oC had a higher rate of ATP production than the mice at 25oC.

(B) The mice at 10oC had a lower metabolic rate than the mice at 25oC.
(C) The mice at 25oC weighed less than the mice at 10oC.
(D) The mice at 25oC were more active than the mice at 10oC.

85. Which of the following best illustrates the flow of information required for the synthesis of proteins encoded in
the genome of a retrovirus?

(A)

(B)

(C)

(D)

86. Which of the following best describes the role of and in the process of photosynthesis?
(A) is required for the chemiosmotic production of during photosynthesis.
(B) and are necessary to initiate the Krebs cycle in photosynthesis.
(C)andare carriers of chemical energy that is used in the production of carbohydrates.

(D) and are required to boost electrons to a higher energy state in photosystemsand.

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87.

Figure 1. The relative concentrations of both the cyclin and components of

Maturation promoting factor, , is a cyclin- complex that catalyzes the phosphorylation of other proteins
to start mitosis. The activity level of is dependent on the relative concentrations of the cyclin and
components of (Figure 1).

Based on Figure 1, which of the following describes the role of cyclin in the regulation of the cell cycle?
(A) During phase, the cyclin level decreases to signal the start of the resting phase of the cell cycle.
(B) Duringphase, the cyclin level peaks, resulting in an increased binding frequency with.

(C)Duringphase, the cyclin level remains the same because replication is occurring.
During phase, the cyclin level remains low, causing activity to decrease, which leads cells to
( initiate mitosis.

88. A researcher is investigating the effects of a chemical that makes thylakoid membranes permeable to hydrogen
ions ( ). Which of the following is the most likely direct effect of adding the chemical to plant cells?
(A) The plant cells will produce less .
(B) The chloroplasts will generate less.

(C) Chlorophyll will require less light energy to excite its electrons.
(D) The plant cells will split fewer water molecules into hydrogen ions and oxygen.

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89.

The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these
two segments would differ?
(A) Segment 1 would not code for mRNA because both strands have T, a base not found in RNA.
(B) Segment 1 would be more soluble in water than segment 2 because it has more phosphate groups.
Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hy
(C)

(D) Segment 1 must be from a prokaryote because it has predominantly A-T base pairs.

90. A student claims that the chromosome contains the sex-determining region gene, known as the gene,
which causes male fetuses to develop testes.

Which of the following provides correct information about cell signaling that supports the claim?
The gene produces a protein that binds to specific regions of in certain tissues, which
(A)
affects the development of these tissues.
The gene produces a protein that deletes portions of the chromosome in males so that male
( characteristics can develop.
The gene produces an segment that is exported from specific cells and targets the
( developing gonads.
(D) The gene is found only in tissues of the developing gonads.

91. A researcher claims that increasing the environmental temperature by will double the rate of an enzyme-
catalyzed reaction. To test the claim, the researcher designs an experiment that uses a particular enzyme
isolated from plants. The design of the experiment is presented in Table 1. For each test tube in the experiment,
the researcher will measure the rate of product formation.

Test Tube Temperature ( ) Substrate Added Enzyme Added Pretreated by Boiling

1 15 Yes Yes No
2 25 No Yes No
3 25 Yes No No
4 25 Yes Yes No
5 25 Yes Yes Yes
6 35 Yes Yes No

Which of the following statements best helps justify the inclusion of test tube 5 as a control in the experiment?

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(A) It will provide a measurement of product formation in the absence of the substrate.
(B) It will provide a measurement of product formation in the presence of a denatured enzyme.

(C) It will show the effect of doubling the amount of substrate on the rate of product formation.
(D) It will show the effect of increased enzyme activity on the rate of product formation.

92. Researchers determined the average amount of time that a particular type of eukaryotic cell spends in each phase
of the cell cycle. The data collected by the researchers are represented in Figure 1.

Figure 1. The average amount of time spent by a particular type of eukaryotic cell in each phase of the cell cycle

Based on Figure 1, what percent of the time required to complete a full cycle do the cells typically spend in
interphase?
(A)
(B)
(C)

(D)

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93. A model of the plasma membrane showing several biological molecules, including a transmembrane protein,
is shown in Figure 1.

Figure 1. Phospholipid bilayer with transmembrane protein

Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?
(A) Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.

Interactions of the peptide bonds of the protein with the membrane will affect the rate at which
( substances can cross the membrane.
(C) Interactions of the protein and phospholipids increase membrane fluidity.
Interactions of the quaternary structure of the protein will increase hydrogen bonding in the membrane
( and make the membrane less fluid.

94. Which of the following best explains why triploid bananas do not produce seeds?

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The cells of the banana plant are unable to replicate , thus preventing cell division and limiting
( growth.
(B) The banana plants lack enough genetic diversity to properly hybridize.
The production of gametes is disrupted because of unequal pairing of homologous chromosomes during meiosis.
(C)

(D) The production of seeds is not required because triploid plants produce gametes without fertilization.

95. A student analyzed a viral genome and found that the genome had the following nucleotide composition.

• 28% adenine

• 20% thymine

• 35% cytosine

• 17% guanine

Which of the following best describes the structure of the viral genome?
(A) Double-stranded DNA
(B) Single-stranded DNA

(C) Double-stranded RNA

(D) Single-stranded RNA

96. Which of the following best describes the role of water in photosynthesis?
(A) Water is the only source of protons for the formation of a proton gradient.
(B) Water molecules donate electrons to the electron transport chain.

(C) Water molecules combine with stored carbon molecules to produce glucose.
(D) Water is the terminal electron acceptor for electrons that pass through the electron transport chain.

97. Researchers studying cell cycle regulation in budding yeast have observed that a mutation in the CDC15 gene
causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of
the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?
(A) The yeast cells will transition out of but will fail to complete the phase.
(B)The yeast cells will initiate mitosis but will fail to complete thephase.
(C) The yeast cells will replicate their chromosomes but will fail to complete cytokinesis.

(D) The yeast cells will replicate their organelles but will fail to complete the S phase.

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98. A group of researchers cultured yeast cells in a nutrient-rich environment and a nutrient-poor environment
and observed the duration of the stages of their cell cycles. The results of their study are summarized in Table
1.

Table 1. Duration (in minutes) of yeast cell cycle phases in a nutrient-rich environment and a nutrient-poor
environment

Cell Cycle Stages Nutrient-rich environment Nutrient-poor environment

and 23 33
Mitosis 48 61
20 57
Cytokinesis 5 10

The cell cycle of yeast cells grown in the nutrient-poor environment is approximately what percent of the cell cycle
of yeast cells grown in the nutrient-rich environment?
(A) 168

(B) 127
(C) 179
(D) 160

99. Saccharomyces cerevisiae is a diploid yeast species that can reproduce either sexually or asexually. An
experiment was performed to induce mitotically dividing S. cerevisiae cells in to undergo meiosis. Which of
the following best describes the steps these cells will follow to form gametes?
The first division will result in crossing over between homologous chromosomes, and the second
( division will reduce the original number of chromosomes by half in the daughter cells.
The first division will reduce the number of chromosomes by half for each daughter cell, and the second
( division will result in each daughter cell having one-fourth of the original number of chromosomes.
The first division will move single chromatids to each daughter cell, and the second division will double
( the number of chromosomes in each daughter cell.
The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will m
(D)

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