ap bio 3 and 4 Flashcards


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1

High levels of certain plant nutrients in runoff can lead to rapid growth of algae (an algal bloom) in aquatic ecosystems. These algal blooms are generally followed by algal death and decomposition, which consumes large amounts of dissolved oxygen in the water and results in oxygen levels insufficient to support aerobic respiration. This process is known as eutrophication. The amount of algae present in a body of water can be estimated from the amount of chlorophyll a in a sample of the water. A researcher studying eutrophication collected samples at different times of the year in a freshwater ecosystem. The samples were analyzed for total nitrogen and chlorophyll a concentration (Figure 1) as well as total phosphorus and chlorophyll a concentration (Figure 2).

A. The concentration of chlorophyll

B. The concentration of total nitrogen and phosphoru

C. The slope of the trend line showing the rate of change

D. The variance of the data points from the trend line

A

2

Investigators studied the interactions between two different proteins, protein I and protein II. Each protein has two structural domains (Figure 1) that represent different functional parts of the protein. Different combinations of the protein domains were tested for their ability to bind to a known DNA sequence, interact with each other, and activate transcription. The results are shown in Table 1.

Which of the following is the most likely result of testing a combination of domains G and M?

A. No functionality

B. DNA binding only

C. Transcriptional activation only

D. Protein-protein interaction only

D

3

Based on the data from the investigation, which of the following is the best scientific question about organisms living in water that is polluted with organic solvents?

A. Do organisms without pigments have a selective advantage in polluted environments?

B. Will organisms living in polluted environments exhibit detrimental effects from an increased permeability of their cellular membranes?

C. Will organic solvents from the environment become incorporated into the cell membranes of organisms living in polluted environments?

D. Should governments place more stringent restrictions on the release of organic solvents into aquatic ecosystems?

B

4

Assuming a negligible pressure potential, which of the following best predicts the net movement of the small diffusible solutes and water in the second experiment (Table 2) ?

A. Small diffusible solutes will diffuse into the grape cells, followed by water.

B. Small diffusible solutes will diffuse out of the grape cells and water will diffuse into the cells.

C. Small diffusible solutes will diffuse out of the grape cells, followed by water.

D. Small diffusible solutes will diffuse into the grape cells and water will diffuse out of the cells.

A

5

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

B

6

The diagram below shows energy changes in a specific chemical reaction with and without the addition of an enzyme to the reaction.

Which of the following questions can best be answered by the diagram

A. Does the addition of an enzyme reduce the activation energy required for a reaction?

B. Does the addition of an enzyme result in the formation of covalent bonds?

C. Does the addition of an enzyme produce a greater amount of products?

D. Does the addition of an enzyme change the pathway for the reaction?

A

7

Researchers investigated the dynamics of a reaction catalyzed by an enzyme. The researchers prepared a series of reactions, each with the same concentration of enzyme but with different concentrations of substrate. The researchers measured the amount of product in each reaction mixture after 5 minutes. The results are shown in Figure 1.

Which of the following questions best addresses whether a particular inhibitor is competitive or noncompetitive?

A. Does the inhibitor bind more tightly to the substrate or to the enzyme

B. Can the inhibitor be converted to product by the enzyme?

C. How much inhibitor is necessary to completely inhibit the activity of the enzyme?

D. Does the inhibitor bind to an allosteric site or the active site of the enzyme?

D

8

A researcher is investigating the effects of a chemical that makes thylakoid membranes permeable to hydrogen ions H+. Which of the following is the most likely direct effect of adding the chemical to plant cells?

A. The plant cells will produce less NADPH

B. The chloroplasts will generate less ATP

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.

B

9

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 pH of the cultures at 5-minute intervals as the bacteria metabolized the glucose into lactic acid. The data are shown in Table 1. BIG AHH CHARTTTT

Which of the following was the dependent variable in the researcher’s experiment?

A. TIme

B. pH

C. Glucose concentration

D. Lactic acid concentration

B

10

Over 100 different types of G-protein-linked receptors have been observed in eukaryotes, including scent receptors in animals, mating-signal receptors in yeasts, and light-sensing proteins in vertebrates. The proton pumps of bacteria have protein structures similar to G-protein-linked receptors. Based on this information, which of the following scientific questions will best guide research on the evolution of G-protein-linked signal transduction?

A. Did the G-protein-linked signal transduction pathway in eukaryotes arise from a precursor in prokaryotes?

B. Are G-protein-linked receptors acquired from the environment as they are needed?

C. Do eukaryotes require symbiotic prokaryotes in order to use G-protein-linked receptors?

D. Do single-celled organisms have more efficient cell communication than do multicellular organisms?

A

11

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?

C. Do these species all perform the same action when the concentration of the signaling molecules is high enough?

D. Did these species evolve from the same common ancestor that is still living today and uses the same receptors?

B

12

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). AHH UN CHARTO

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 G2 serve to prevent the transmission of mutations?

A

13

Hydrangea flowers differ in color based on interactions between a pigment in the flower cells and aluminum ions dissolved in water absorbed from the soil. When aluminum ions are present, the pigment is blue; when aluminum ions are absent, the pigment is pink. The amount of aluminum ions the plant can absorb is dependent on the pH of the soil.

Which of the following questions will best help a researcher design an experiment to learn about the relationship between hydrangea flower color, aluminum, and pH?

A. How do aluminum-pigment interactions change the structure of the pigment and flower color?

B. Can the pigment be used as an indicator of pH, because flower color depends on pH and aluminum?

C. Does an increase in hydrogen ion concentration affect the ability of the pigment to dissolve in water?

D. What will be the flower color of hydrangeas grown in soils of varying pH with or without aluminum?

D

14

Mutations in the MYO6 and POU4F3 genes have been associated with a form of hereditary hearing loss in humans. Researchers studying the genes have proposed that POU4F3 encodes a transcription factor that influences the regulation of MYO6.

Which of the following questions will best help guide the researchers toward a direct test of their proposal?

A. Have mutations in other genes also been associated with hearing loss?

B. In what types of cells are the mutant forms of the POU4F3 genes expressed?

C. Are mutations in the MYO6 and POU4F3 genes also found in mice?

D. Do mutations in the POU4F3 gene affect MYO6 mRNA levels in cells?

D

15

Cystic fibrosis is a recessively inherited disorder that results from a mutation in the gene encoding CFTR chloride ion channels located on the surface of many epithelial cells. As shown in the figure, the mutation prevents the normal movement of chloride ions from the cytosol of the cell to the extracellular fluid. As a consequence of the mutation, the mucus layer that is normally present on the surface of the cells becomes exceptionally dehydrated and viscous.

An answer to which of the following questions would provide the most information about the association between the CFTR mutation and the viscous mucus?

A. Is the mucus also secreted from the cells through the CFTR proteins?

B. How does the disrupted chloride movement affect the movement of sodium ions and water by the cell?

C. How does the mutation alter the structure of the CFTR proteins?

D. What is the change in nucleotide sequence that results in the CFTR mutation?

B

16

Iron is an essential nutrient that is acquired by organisms from the environment. When intracellular levels of iron are relatively high, living cells synthesize an iron-storage protein called ferritin.

The induction of ferritin synthesis by iron was investigated in rats. Figure 1 shows the results of an experiment in which cellular levels of ferritin protein were measured in the presence or absence of iron and actinomycin D, a drug that inhibits transcription.

Which of the following biotechnology approaches could be used to identify ferritin mRNA in a sample of total cellular RNA?

A. RNA samples could be directly cloned into a DNA plasmid, grown in bacteria, and tested for the ability to bind iron.

B. RNA samples could be separated by size using agarose gel electrophoresis and incubated with labeled single-stranded DNA molecules that are complementary to the ferritin mRNA.

C. RNA samples could be converted to protein and subsequently cut with a restriction endonuclease that recognizes DNA sequences.

D. RNA samples could be examined under a high-power microscope to visually identify the ferritin mRNA.

B

17

A population of fruit flies (Drosophila pseudoobscura) grown on a typical nutrient source was separated into several growth chambers. Each of the new chambers was assigned a different source of carbohydrates for nutrition, either starch or maltose, and maintained for many generations (Figure 1).

CHARTS AND AHH

Which of the following best represents the null hypothesis for the experiment detailed in Figure 1 ?

A. The mating preferences of flies are not dependent on the nutrient source on which they are grown.

B. Prolonged exposure to a different diet can change behavior in fruit flies

C. When crossed, flies grown on the same medium will not produce viable offspring.

D. Growing flies in a confined chamber will not create a barrier to mating in fruit flies

A

18

Some cells release active signaling proteins when membrane-bound precursor proteins are cleaved by proteolytic enzymes. The signaling proteins can then bind to receptors on the surface of a target cell, thereby activating an intracellular signaling pathway and eliciting a response from the target cell.

This mechanism of activating receptor-binding signaling proteins has been observed in a variety of organisms from bacteria to humans. Many of the enzymes responsible for proteolysis of membrane-bound precursor proteins have been isolated and characterized.

Which of the following questions would be most appropriate to investigate whether the proteolytic enzymes are evolutionarily conserved among species?

A. Are the genes encoding the proteolytic enzymes expressed in the same cell types in all species?

B. Once the precursor proteins of different species are cleaved, do the active signaling proteins bind to the same receptors on different target cells?

C. If a proteolytic enzyme from one species is incubated with a precursor protein from another species, does correct cleavage occur?

D. Are the proteolytic enzymes synthesized in the rough endoplasmic reticulum of all species?

C

19

The phylogenetic trees in Figures 2 and 3 depict two different phylogenies of the same populations of sticklebacks. Which of the following questions will best help determine which tree represents the most accurate phylogeny?

A. Is the EDA gene as representative of the differences between the populations as the 25 random genes that were examined for Figure 3?

B. Are the low-plated populations found only in freshwater and the high-plated populations found only in saltwater environments?

C. Is the common ancestor of the organisms represented in Figure 2 different from the common ancestor of the organisms represented in Figure 3!

D. Is the expression level of the EDA gene analyzed in Figure 2 significantly greater than the expression levels of the 25 genes analyzed in Figure 3?

A

20

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds.

Which of the following procedures was most likely followed to determine the change in beak size?

A. A few finches were trapped in 1981 and again in 1987, and their beak sizes were compared.

B. The beak size in fifteen finches was measured in 1987, and the beak size in the original finches was determined by estimation.

C. The beak size in a large number of finches was measured every year from 1981 to 1987.

D. Finches were captured and bred in 1981, and the beak size of the offspring was measured.

C

21

Which of the following questions about the origin of life on Earth is most scientifically testable?

A. Why were the earliest life-forms created using only twenty amino acids?

B. Did life originate to make the universe a better place?

C. Was catalytic RNA used by ancient organisms as a stepping stone to acquire protein enzymes?

D. Can simple organic molecules form spontaneously in an oxygen-free atmosphere?

D

22

Hydrangea macrophylla is a species of plant with blue or pink flowers. Flower color in Hydrangea macrophylla plants is thought to be determined primarily by soil conditions rather than by inherited differences. Which of the following will provide the most direct evidence that flower color in Hydrangea macrophylla is due primarily to soil conditions?

A. Comparing DNA sequence information for Hydrangea macrophylla to DNA sequence information for a different species of flowering plant

B. Performing a genetic cross between a pink-flowered plant and a blue-flowered plant and then determining the ratio of phenotypes in the offspring

C. Growing cuttings from the same Hydrangea macrophylla plant under controlled conditions that vary only with regard to soil pH

D. Analyzing fossilized remains of an ancestral species that grew in geographic areas similar to the habitats of modern Hydrangea macrophylla

C

23

A LIL CHART

Which of the following is an appropriate null hypothesis for the student’s experiment?

A. The absence of light negatively affects the mass of the grass.

B. An increase in light promotes grass growth.

C. A change in light intensity changes the rate of grass growth.

D. The presence of light has no effect on the mass of the grass.

D

24

In the early 1970s, researchers hypothesized that carbon was the limiting nutrient in many aquatic ecosystems. To test this hypothesis, the researchers divided a small lake in two roughly equal halves with an impermeable curtain that was fastened and sealed to the bedrock of the lake. Beginning in 1971 the researchers treated one side of the lake with sucrose and the other side with both sucrose and phosphate. From 1971 to 1983 the researchers monitored the phytoplankton biomass in both parts of the lake. The results are shown in Figure 1.

Which of the following treatments would have been the best control treatment for the experiment?

A. An untreated section of the lake

B. A section of the lake that was treated with phosphate but not sucrose

C. A different lake that was treated with sucrose and phosphate

D. A small pool of the lake water maintained in a controlled laboratory environment

A

25

Researchers investigated the habitat preferences of two species of garter snakes, Thamnophis sirtalis and Thamnophis atratus. To create a choice chamber, the researchers built a meshed enclosure and positioned one end of the enclosure at the edge of a small pond. Zone I of the enclosure was located in the water, whereas zone IV of the enclosure was located 2–3 meters away from the water, as represented in the figure below. Snakes inside the enclosure were able to move freely between zones.

Which of the following additions to the experimental design will best help test whether the observed habitat preferences were the result of competition between species?

A. Placing two individuals from the same population together inside the enclosure

B. Introducing different types of plants into the enclosure together with the snake

C. Doubling the number of repetitions for the experimental treatment with T. atratus alone

D. Repeating the investigation with an enclosure that is twice as long as the original

A

26

A scientist is evaluating a proposal for raising large numbers of fish in ocean pens for human consumption. As part of the evaluation, the scientist is designing a plan for investigating how the fish in the ocean pens might affect nearby ecosystems.

Which of the following is the most appropriate factor to use as the dependent variable in the experimental investigation?

A. The amount of metabolic wastes in the water where the fish are being raised

B. The water temperature in the natural habitat of the fish being studied

C. The types of fish that are preferentially consumed by humans

D. The amount of time it takes for fish to digest a meal

A

27

Water in a pond contaminated with the weed killer atrazine is suspected of inhibiting metamorphosis in northern leopard frogs. A team of scientists collected fertilized northern leopard frog eggs from a different pond that is not contaminated. Which of the following is the best experimental design to determine whether atrazine is responsible for inhibiting metamorphosis in northern leopard frogs?

A. Place half of the fertilized eggs in a pool of water with the same concentration of atrazine as the contaminated pond and place the other half of the fertilized eggs in a pool of water that has no atrazine. Monitor the development of the embryos through metamorphosis into adulthood.

B. Place all of the fertilized eggs in a pool of pond water with the same concentration of atrazine as the contaminated pond and compare the number of frogs that reach metamorphosis to those that reach adulthood in the contaminated pond.

C. Allow all fertilized eggs to develop into adults. Expose one-third of the frogs to one-half of the concentration of atrazine in the contaminated pond and expose another one-third of the frogs to the same concentration of atrazine as the contaminated pond. Leave the last one-third of the frogs in water with no atrazine and note any adverse changes in the physical condition of the atrazine-treated frogs in three months.

D. Divide the fertilized eggs into three groups and expose each group to a different concentration of atrazine. Release the eggs back into the contaminated pond and check for metamorphosis after three months.

A

28

Which of the following describes the relationship between the amount of chlorophyll a in a water sample and the concentration of nitrogen in that sample?

A. As the concentration of chlorophyll a increases, the concentration of nitrogen decreases.

B. The concentrations of nitrogen and chlorophyll a are directly correlated.

C. The concentrations of chlorophyll a and nitrogen increase throughout the year.

D. There is no relationship between the concentrations of chlorophyll a and nitrogen.

B

29

Investigators studied the interactions between two different proteins, protein I and protein II. Each protein has two structural domains (Figure 1) that represent different functional parts of the protein. Different combinations of the protein domains were tested for their ability to bind to a known DNA sequence, interact with each other, and activate transcription. The results are shown in Table 1.

Big ahh chart

Based on the data, which structural domain is most likely required for DNA binding?

A. Domain F

B. Domain G

C. Domain

D. Domain M

A

30

In the first step of an experiment, rat liver cells were exposed for 5 minutes to amino acids labeled with a radioactive isotope. The cells were then washed to stop any further incorporation of radioactive amino acids. The cells were sampled periodically thereafter, and the radioactivity of a certain protein (protein X) was measured in various cell components, as shown below.

Which of the following correctly shows the order in which protein X moves through the cell?

A. Endoplasmic reticulum→Golgi apparatus→lysosomes

B. Endoplasmic reticulum→Golgi apparatus→nucleus→cytoplasm→lysosomes

C. Extracellular space→mitochondria→cytoplasm

D. Golgi apparatus→cytoplasm→lysosomes

E. Cytoplasm→mitochondria→extracellular space\\

A

31

In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion?

A. The cuboidal cell

B. The tetrahedral cell

C. The cylindrical cell

D. The spherical cell

A

32

A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability.

The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above.

Which of the following graphs is the most appropriate representation of the experimental data?

BAR GRAPH W ERROR BAR

33

Figure 1 shows the relative rates of transpiration (water loss) and water intake for a plant over an 18-hour period. Which of the following describes the most likely relationship between transpiration and water intake in the plant?

A. Transpiration from the leaves of the plant stimulates subsequent water intake by the roots of the plant.

B. Transpiration and water intake peak at the same time of day.

C. Water intake by the roots of the plant drives transpiration at the leaves of the plant.

D. Transpiration and water intake have an inverse relationship.

A

34

Trypsin and pepsin are enzymes that function in different areas of the digestive tract. One functions in the stomach, where the pH is between 1.5 and 3.5, while the other functions in the small intestines, where the pH is between 6 and 8.

Based on Figure 1, which of the following best describes where each enzyme functions?

A. Pepsin works in the intestines because the optimal pH for pepsin is basic.

B. Trypsin works in the stomach because the optimal pH for trypsin is basic.

C. Pepsin works in the stomach because the optimal pH for pepsin is acidic.

D. Trypsin works in the stomach because the optimal pH for trypsin is acidic.

C

35

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.

According to the results of this experiment, germination of tobacco seeds during the first week is

A. increased by exposure to light

B. unaffected by light intensity

C. prevented by paper towels

D. accelerated in green-leaved seedlings

A

36

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 pH of the cultures at 5-minute intervals as the bacteria metabolized the glucose into lactic acid. The data are shown in Table 1.

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

the one w plotted points and erros bars on each point

37

The graph in Figure 1 shows the percent saturation of fetal hemoglobin and maternal hemoglobin in humans as a function of the partial pressure of oxygen. Based on the data, which of the following values is closest to the predicted difference in the percent saturation of fetal hemoglobin and maternal hemoglobin at 40mmHg?

A. 10

B. 12

C. 20

D. 40

C

38

Figure 1. Percent survival of normal melanocytes and cancerous melanocyte (melanoma) lines 1 and 2 after treatment with different concentrations of drug X

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

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

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

A. As the concentration of drug X increases, there is an increase in melanoma cell survival.

B. At a concentration above 10 μM, drug X reduces melanoma cell survival.

C. At a concentration below 25 μM, drug X increases survival in all melanoma cell lines

D. At a concentration of 25 μM, drug X has a greater effect on melanoma line 1 than on melanoma line 2.

B

39

Based on the data in Figure 1, which of the following best describes the inheritance pattern of Friedreich’s ataxia?

A. Autosomal recessive

B. Autosomal dominant

C. Sex-linked recessive

D.Sex-linked dominant

A

40

Which of the following statements best describes the results seen in Figure 2 ?

A. Individuals III-2 and III-3 carry two different alleles of the FXN gene, a mutant allele and a wild-type allele. Individual IV-1 inherited two copies of the mutant allele.

B. Individuals III-2 and III-3 carry two different alleles of the FXN gene, a mutant allele and a wild-type allele. Individual IV-1 inherited two copies of the wild-type allele.

C. Individuals III-2 and III-3 both carry two wild-type alleles. Individual IV-1 inherited two copies of the wild-type allele.

D. Individuals III-2 and III-3 III-3 both carry two wild-type alleles, but individual IV-1 inherited one copy of the wild-type allele and one copy of the mutant allele.

A

41

A culture of white-eyed fruit flies (Drosophila melanogaster) was maintained for many generations. Females from the stock white-eyed culture were crossed with red-eyed (wild-type) males. The F1 females were crossed with the white-eyed males from the original culture. The resulting phenotypes of the progeny are summarized below.

There are white-eyed females in the F2 generation because

A. white is a dominant allele

B. the white allele is autosomal

C. a mutation has occurred

D. these F2 females have two white alleles

E. the white allele is located on the Y chromosome

D

42

Based on the data, which of the following best describes the relationship between light and the degradation of mRNA G and mRNA H?

A. Exposure to light causes the degradation of both mRNA G and mRNA H.

B. mRNA G and mRNA H degrade at the same rate during morning exposure to light.

C. A longer exposure to light increases the rate of mRNA G degradation but not of mRNA H degradation.

D. Exposure to more-intense afternoon light causes both mRNA G and mRNA H to degrade more rapidly in the afternoon than in the morning.

C

43

Researchers studying new viruses analyzed the genetic material found in four different virus samples to determine the percent nitrogen base composition of each virus. The data are shown in the table.

Which of the following samples most likely contains a double-stranded RNA virus?

A. Sample 1

B. Sample 2

C. Sample 3

D. Sample 4

A

44

The table below describes the action of two genes involved in the regulation of nervous system development in the nematode C. elegans.

Which of the following claims is best supported by the data?

A. Gene A promotes neuron development; gene B promotes programmed cell death in neuronal precursors.

B. Gene A promotes programmed cell death in neuronal precursors; gene B promotes neuron development.

C. Gene B must be active before gene A can function.

D. Gene B must be inactive before gene A can function.

A

45

Which of the following can be inferred from the data in the table?

A. Ground beetles do not emigrate from the habitat in which they live.

B. Insectivorous birds prefer to eat light-tan beetles rather than dark-brown beetles.

C. Ground beetles have higher rates of survival in habitats with loam soil.

D. Insectivorous birds are predators of this species of ground beetle.

E. The reproductive success of beetles in habitats with sandy soils is greater than that of beetles in habitats with loam soils.

D

46

A population of fruit flies (Drosophila pseudoobscura) grown on a typical nutrient source was separated into several growth chambers. Each of the new chambers was assigned a different source of carbohydrates for nutrition, either starch or maltose, and maintained for many generations (Figure 1).

After a year, male and female flies were paired up in different combinations. The instances of mating between the males and females grown on the same nutrient source and males and females grown on different nutrient sources were recorded (Table 1).

Which of the following combinations of flies showed the highest number of mating instances?

A. Males grown on maltose paired with females grown on starch

B. Males grown on starch paired with females grown on starch

C. Males grown on maltose paired with females grown on maltose

D. Males grown on starch paired with females grown on maltose

B

47

Figure 1. For paired groups of organisms, a comparison of the number of amino acid substitutions in cytochrome C with the time since the groups diverged from a common ancestor

Researchers analyzed the amino sequence of the protein cytochrome c in various groups of organisms and determined the number of amino substitutions that have occurred in the different groups of organisms. They plotted the data with respect to the time since divergence of the members of paired groups from a common ancestor (Figure 1). Based on the data, which of the following organisms are most distantly related?

A. Birds and mammals

B. Mammals and reptiles

C. Fish and land vertebrates

D. Insects and vertebrates

D

48

Scientists are interested in determining the evolution of seven lizard species found on different islands of the Canary Island group. They isolated DNA from individuals of each species and sequenced the mitochondrial gene that encodes cytochrome b. The numbers of genetic differences between species are shown in the table below.

Based on the data in the table, which of the following lizard species are most closely related?

A. Species C and species B

B. Species E and species D

C. Species F and species

D. Species G and species A

B

49

Chytridiomycosis is a potentially lethal fungal infection that adversely affects some frog populations. The incidence and severity of the fungal infection can vary over time. Which of the following statements best describes the changes in the frog population that are depicted in the model above?

A. The fungus that infected the frog population was initially virulent but it later became harmless. Based on the trend over the past few years of the study, the fungus has become extinct.

B. Infected individuals gradually died out, and genetically resistant individuals became more common. The frog population recovered because of the increased frequency of resistant individuals.

C. The patterns of the curves on the graph indicate a sudden increase in the severity of the fungal infection. A large proportion of the frog population died because the individuals could not evolve fast enough.

D. The size of the frog population decreased sharply upon initial contact with the fungus. The fungus eventually became symbiotic with individual frogs, and the frog population began to recover.

B

50

Which of the following best describes the reproductive ability of C. elegans following the ARD induced in the first experiment?

A. Mating with a well-fed male consistently produced more offspring than did reproduction via self-fertilization.

B. The numbers of progeny produced by self-fertilization and by mating with well-fed males were not statistically different.

C. C. elegans stopped reproducing after 20 days without food.

D. There was no relationship between days without food and average brood size.

A

51

In the Arctic Ocean, the predominant primary producers are phytoplankton. Phytoplankton are consumed by zooplankton, which in turn are eaten by codfish. In years when there is more open water (less ice coverage), there are more zooplankton and fish than in years with less open water (more ice coverage). Based on the graph above, the difference is most likely because

A. when there is less open water, light is blocked from the zooplankton, so they cannot produce as much food for the fish

B. when there is more open water, the temperature is warmer, so the zooplankton and fish populations increase in size

C. the ice blocks the light, so in years with more ice coverage, there is less photosynthesis by the phytoplankton

D. the ice increases the light available for photosynthesis, so primary production increases and zooplankton populations increase in size

C

52

One model of a sustainable fisheries practice is for individual fish to be removed from a natural population at a rate equal to the highest possible growth rate of an ideal population. The graph above represents a population of bluefin tuna living along the Atlantic coast. At which labeled point in the graph is the population growth rate the highest?

A. I

B. II

C. III

D. IV

C

53

Which of the following best estimates the population size of the sea lions in 2000 based on the data shown in Figure 1?

A. 100,000

B. 125,000

C. 175,000

D. 285,000

C

54

To investigate the effects of ground-level ozone pollution on different species of plants, researchers recorded the number of plants in a certain area that had ozone-induced leaf damage. Based on the results of the survey shown in Table 1, which of the following plant species was most affected by ozone pollution?

A. Ash

B. Cherry

C. Sweet Gum

D. Wild Grape

D