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Which of the following observations would best support the alternative hypothesis described above?

B

In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane.

Which of the following scientific questions will best help researchers determine when the nontaster allele arose in the evolutionary history of the selected primates?

B

Does the nontaster allele exist in any nonhuman primate populations?

What evolutionary advantage does compartmentalization of core metabolic processes offer eukaryotes?

C

Evolution of a nucleus in eukaryotes separates the processes of transcription and translation and they can be regulated separately.

Which of the following best explains the relationship between the different bumblebee species living in the same area?

B

The bumblebees have undergone niche partitioning due to competition.

Competition for food would probably be most severe between two

B

closely related species in similar niches

Which of the following best describes the production of DMSP by coral and coral symbionts?

Responses

B

A negative feedback mechanism that reverses the environmental change

In Darwinian terms, the fittest individuals of a species are those that

E

leave the greatest number of reproducing descendants

Which of the following best explains the observations concerning DDT resistance in mosquitoes?

Natural selection favors DDT-resistant mosquitoes that are already present in a population when DDT exposure occurs.

All of the following are density-dependent factors that limit animal populations EXCEPT

A

weather

Carbon dioxide most likely enters a cell through which of the following processes?

A

Simple diffusion through the membrane

Which of the following best explains the reactions of these enzymes?

B

Amylase aids in the addition of a water molecule to break covalent bonds whereas glycogen synthase aids in the removal of a water molecule to form covalent bonds.

Which of the following best describes the cause of the rapid increase in the number of mammalian species between 65 and 55 million years ago?

C

After the dinosaur extinction, many ecological niches became available, leading to the adaptive radiation of mammals.

The features of this model provide evidence for which explanation of why all growing strands are synthesized in a 5′ to 3′ direction?

D

The phosphate group, attached to the 5′ carbon of the dTMP, forms a covalent bond with the oxygen atom attached to the 3′ carbon of the growing strand.

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

B

The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.

When DNA replicates, each strand of the original DNA molecule is used as a template for the synthesis of a second, complementary strand. Which of the following figures most accurately illustrates enzyme-mediated synthesis of new DNA at a replication fork?

D - Diagram

Which of the following best describes the process responsible for the change in the percent of tuskless female elephants in the Gorongosa National Park population shown in Figure 1 ?

A

Human hunting of elephants with tusks between 1977 and 1992.

Which of the following statements best helps explain the reaction specificity of an enzyme?

C

The shape and charge of the substrates are compatible with the active site of the enzyme.

The molecular structures of linoleic acid and palmitic acid, two naturally occurring substances, are shown in the figure.

C

Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.

Scientists investigated the role that beak depth plays in the ability of one species of seed-eating finch to reproduce. The scientists calculated the average beak depth of finches in mating pairs and then observed whether or not the pairs produced at least one offspring that survived to the next season. The data are represented in Figure 1.

Figure 1. Beak depth and offspring survival in a species of finch

Based on the data in Figure 1, which of the following best describes the concept illustrated?

A

Parental pairs with a specific beak depth had the highest reproductive fitness.

Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions?

B

They have highly folded membranes.

The food web represented above does not include bacteria and fungi. Which of the following best describes a consequence of having no bacteria and fungi in the food web?

A

Grasses will have no direct access to chemical components recycled from dead organisms.

Which of the following is the most likely result at the completion of the project?

B

The biomass of coyotes will be dramatically reduced.

Which species would most likely represent humans if they were part of this ecosystem?

C

C

The phenotypic variation in behavior between the two populations can best be described as resulting from

C

artificial selection

The researcher claims that there is no selective advantage to fur color, so light and dark fur color phenotypes are present in similar frequencies in the fourth generation of this mouse population. Based on the data in Figure 1, which of the following best evaluates this null hypothesis?

A

The null hypothesis is rejected, because the change to a darker background color led to an increase in the dark-colored fur phenotype.

Gaucher disease type 1 (GD1) is a recessive genetic disease that affects 1 in 900 individuals in a particular population. GD1 is caused by a mutation in the enzyme glucocerebrosidase.

Assuming the population is in Hardy-Weinberg equilibrium, calculate the frequency of the wild-type (nonmutant) allele for the enzyme glucocerebrosidase.

C

0.967

Two populations of a species of squirrel are geographically isolated from each other. Although they have the same population density, one population is significantly larger in number than the other. A new bacterial disease, which is easily spread and extremely virulent, affects both populations at the same time. Which of the following is the best prediction of how the new disease will affect the two populations?

C

The smaller population will be more affected than will the larger population, because the smaller population has less genetic variation than the larger population has.

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum.

Which of the following best describes a process that occurs within the Golgi complex?

A

Enzymatic modification of newly synthesized integral membrane proteins

A particular genetic disorder is associated with a single gene with two alleles. Individuals with two recessive alleles are affected. The prevalence of the disorder is 1 in 6,600.

Assuming the population is in Hardy-Weinberg equilibrium, which of the following is closest to the frequency of carriers in the general population?

C

0.02430

Dr. Robert Hazen has worked to develop a hypothesis that explains the origin of life on Earth. His work has focused on hydrothermal vents, which are cracks in the ocean floor. Water heated by molten rock beneath the crust escapes from these vents at very high temperatures, producing hot, high‑pressure environments at the vents on the ocean floor.

In order to provide evidence that these vents may be areas where life originated, which of the following states a null hypothesis Hazen might have used to begin his research?

B

The temperatures and pressures found in hydrothermal vents resemble conditions described in currently accepted origins of life hypotheses.

Which of the following diagrams best represents hormone-activated gene expression?

PICTURE A

A particular gene has two alleles, a dominant allele A and a recessive allele a. The frequency of allele A is 0.55.

If the population is in Hardy-Weinberg equilibrium with respect to the gene, then what is the expected frequency of genotype Aa?

D

0.495

Zebra mussels are an invasive species that has become widely established throughout the United States. Figure 1 shows the percent change in the population sizes of selected groups of organisms in the Hudson River since the introduction of zebra mussels. In this study chlorophyll-containing bacteria are considered phytoplankton and all other bacteria are considered bacterioplankton.

Figure 1. Change in biomass of selected Hudson River organisms after the introduction of zebra mussels

Which of the following hypotheses about the effect of zebra mussels on the Hudson River community is best supported by the data in Figure 1 ?

C

The reduction in primary productivity has resulted in an unstable community that will eventually collapse.

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 ?

C

How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?

Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function.

Which of the following outcomes will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface?

Responses

D

Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.

Which of the following predicts the most likely ecological problem that would occur if guppies are introduced into new areas to control the mosquito population?

The guppies might have no natural predators, which will result in a dramatic increase in the guppy population and an increase in competition for other native species.

In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a reaction catalyzed by ATP synthase molecules that are embedded in the thylakoid membrane.

Which of the following statements provides evidence to support the claim that no ATP will be synthesized in the absence of a proton gradient across the thylakoid membrane?

C

No ATP is synthesized when channel proteins that allow the free passage of protons are inserted into the thylakoid membrane.

Researchers were studying species diversity in a savanna rangeland community in southwest Queensland, Australia. Researchers counted the numbers of plants species in four different categories at two nearby sites within the savanna rangeland; one lightly grazed by herbivores and one heavily grazed by herbivores (Figure 1).

Which of the following best predicts the results of a drought in the savanna research area with regards to community resilience to this environmental change?

B

The lightly grazed area is likely to recover more quickly from the drought due to greater biodiversity.

Low doses of antibiotics are often added to livestock feed to increase production. Studies have shown that bacterial populations constantly exposed to the sublethal doses can evolve resistance to the antibiotics. A research group claimed that when a population of bacteria are constantly exposed to sublethal doses of streptomycin, their fitness declines due to the increased energy requirements for survival in the presence of the antibiotic. For subsequent studies, the researchers wish to determine whether adding a low, sublethal dose of an additional antibiotic causes further decline in the fitness of the bacteria.

Which of the following best represents the next step the researchers should take with respect to experimental design?

Group 1: low dose of streptomycin + no dose of additional antibiotic

Group 2: low dose of streptomycin + low dose of additional antibiotic

Group 1: low dose of streptomycin + no dose of additional antibioticGroup 2: low dose of streptomycin + low dose of additional antibiotic

There is no significant difference between the extinction rate of animals between 1950 and 2000 in China and the background extinction rate.

Which of the following describes a mutation that would lead to an increase in the frequency of nondisjunction?

C

A mutation affecting checkpoint 3 proteins that prevents attachment of spindle fibers

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?

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?

If the normal spermatogenesis is disrupted, the gametes can have different chromosomes than expected. Which of the following is the most likely cause of one of the four gametes having two X chromosomes and one having neither an X nor a Y chromosome?

D

Nondisjunction of the X chromosome during meiosis II

Which of the following is the mean number per cross of F2 generation offspring that are the result of crossing over?

B

2.2

Which of the following best explains why a cell's plasma membrane is composed of two layers of phospholipids rather than just a single layer?

A

Having two oppositely oriented layers of phospholipids allows only the hydrophilic heads to interact with water inside and outside of the cell.

Which of the following statements best explains the processes of passive and active transport?

B

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

Pesticides are chemicals that are often sprayed on crops to kill plant-eating insects, preventing damage to the crops. While pesticides are effective initially, many researchers claim that any single pesticide will see reduced effectiveness in as little as ten to fifteen years.

Which of the following best supports the claim by scientists that the pesticides will eventually lose their effectiveness?

B

Insects that are naturally resistant to the pesticide will survive and reproduce more than the insects that are sensitive to the pesticide.

Which of the following correctly identifies the dependent and independent variables in this experiment?

B

The percentage of plants showing phototropism is the dependent variable, and the color of the light is the independent variable.

Based on the cladogram, which of the following are the traits shared between ferns and pines?

C

Embryo and xylem only

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?

D

Small, water-soluble molecules

Which of the following best explains how water is able to move upward from the roots of a plant, through its xylem in the stem, and out to the leaves?

D

Water and the xylem are both polar. Water molecules have the ability to form hydrogen bonds with each other and with the walls of the xylem.

The transport of a substance across a plasma membrane of a specific organelle requires energy. The rate at which the transport takes place also depends on temperature. A scientist isolated the specific organelle and then used the following treatments to determine the conditions that will result in the maximal transport. All treatments contained the extracted organelle and were maintained at 25°C.

The data from this experiment indicate that maximal rate of transport of protein X at 25°C occurs at an ATP concentration of 1.0μm/mL.

Figure 1. The four ATP concentrations used in the experiment

Which procedure should be done next to gather data needed to meet the scientist's objective?

C

Incubate samples containing 1.0μm/mL of ATP at four temperatures other than 25°C.

Which of the following best explains how the ecological conditions are likely to be different in the two models?

D

In model A the ecological conditions change gradually over a long period of time; in model B the ecological conditions remain unchanged for long periods of time and then change drastically.

Humans vary in their ability to taste the bitter chemical compound phenylthiocarbamide (PTC). The taster phenotype is dominant to the nontaster phenotype. Researchers tested the PTC taster phenotype of individuals from an isolated population. In the sample, 780 individuals were able to taste PTC and 70 individuals were not able to taste PTC.

Assuming the population is in Hardy-Weinberg equilibrium, what is the frequency of the non-taster allele?

Responses

B

0.29

In the spring and summer, the fur of an arctic fox contains a pigment called melanin that gives the fox's fur a dark color. In the fall and winter, the fur of the arctic fox is white.

Which of the following most likely explains how the changing seasons result in changing fur color in an arctic fox?

Responses

A

Environmental factors cause changes in gene expression, resulting in seasonal variations in pigment production.

Which of the following best predicts how the structure and function of pepsin will change as it enters the small intestine?

C

Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease.

Ultraviolet (UV) radiation can damage DNA by breaking weak bonds. Which of the following best explains how this occurs?

B

UV radiation disrupts the double helix structure by breaking the hydrogen bonds between the nitrogenous base pairs.

A scientist interested in investigating how human population trends might affect local animal species' richness stipulates a null hypothesis that animal biodiversity in rural areas will be unaffected in the future by the human population trends shown in Figure 1. Which of the following would best refute this null hypothesis?

B

Urbanization causes habitat fragmentation.

Based on the data, which of the following is the best explanation for the changes in the elk population size between 2000 and 2005 ?

B

Predation by wolves was higher than before 1995.

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?

B

Did these species evolve from a common ancestor that used a similar signaling molecule?

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?

B

The animal's body cells are defective in endocytosis.

Which of the following best describes the primary mechanism of transport whereby carbon dioxide moves from inside a cell to outside the cell?

C

Carbon dioxide passively diffuses between the membrane lipids.

Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1 ?

C

Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.

A cell is treated with a drug that prevents the formation of new lysosomes. The cell continues to transcribe the genes that code for the hydrolytic enzymes that are normally found in lysosomes and continues to translate the mRNAs for those proteins on membrane-bound ribosomes.

The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures?

Responses

D

Golgi complex

Which of the following statements about the rate of CO2 fixation in the two types of plants is supported by the data shown in the figures?

A

At 21% O2, plant type 2 has a lower rate of CO2 fixation than plant type 1 does in both types of soil.

Which of the following observations would best support this alternative hypothesis?

A

Previous dips in plankton abundance coincided with other El Niño events.

Figure 1. A model of an endocrine signaling pathway showing involved body parts and hormones. GnRH = gonadotropin-releasing hormone, LH = luteinizing hormone, and FSH = follicle-stimulating hormone.

Figure 1 shows a model of the endocrine signaling pathway that regulates ovulation.

Which of the following observations would provide evidence of a positive feedback mechanism in this system?

Responses

D

Estrogen from the ovaries stimulates the hypothalamus and anterior pituitary to secrete more GnRH, LH, and FSH.

Which of the following statements is most consistent with the data in Figure 1 ?

D

Snakes display behaviors that allow them to absorb or radiate heat as required.

Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells?

D

Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.

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?

D

Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

Which of the following investigations would enable researchers to test the claim that an increased concentration of algae has a negative effect on the number of aquatic invertebrates in the ecosystem?

C

Counting the number of aquatic invertebrates at different concentrations of chlorophyll a in the water

Which of the following is evidence that eukaryotes and prokaryotes share a common ancestor?

B

All eukaryotes and prokaryotes contain ribosomes.

Which of the following is the strongest evidence supporting the endosymbiont hypothesis?

A

Mitochondria have their own DNA and divide independently of the cell.

Ethylene gas is an organic molecule that serves many cell signaling roles in flowering plants. Which of the following best explains how a positive feedback mechanism involving ethylene works?

A

Cells of ripening fruit produce ethylene, which activates the ripening response in other fruit cells.

Which of the following would be the most appropriate control for this experiment?

C

A test tube containing a piece of exposed camera film submerged in water

Based on Table 1, which of the following best explains the difference in water potential between certain solutions and the grapes?

B

Grape soda and NaCl have a lower water potential because these two solutions caused the grape to lose water.

Which of the following correctly identifies the dependent variable and the independent variable for the experiment?

D

The independent variable is the type of alarm, and the dependent variable is the percent of squirrels responding.

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 (GSK3β) can act either as an oncogene or as a tumor suppressor.

Which of the following best predicts how GSK3β mutations can lead to the development of cancer?

A

Cells with inactive GSK3β fail to trigger apoptosis.

The lionfish is a venomous fish found primarily in the Red Sea and the Indian Ocean. In the 1990s, lionfish were accidentally released into the Atlantic Ocean, where they found abundant resources and favorable environmental conditions. Which of the following scenarios is most likely to result in the lionfish having a major impact on the communities into which they were introduced?

A

With no natural predators, the lionfish population will become very large.

Which of the following is represented by the gradual increase in thickness of the arrows from the top to the bottom of Figure 1?

B

The number of signaling molecules that are produced or activated increases with each step in the pathway.

Oxygen consumption can be used as a measure of metabolic rate because oxygen is

A

necessary for ATP synthesis by oxidative phosphorylation

The function of which of the following organelles directly requires oxygen?

B

Mitochondrion

Which of the following statements best explains the observations represented in Figure 1 ?

C

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

Which of the following best explains the connection between energy, growth, and the maintenance of an ordered system in the experiment?

A

Energy input from light is required for the grass to grow and maintain an ordered structure.

Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them?

D

Rough ER can synthesize and package proteins for export, and smooth ER cannot.

Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment?

A

Cell A, because it has the larger surface-area-to-volume ratio.

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

The observed differences between the groups most likely resulted from differences in the ability of the seedlings to produce which of the following monomers?

picture

Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic acid #2 ?

D

Nucleic acid #1 contains adenine-thymine base pairs, whereas nucleic acid #2 does not.

Which of the following statements best describes how organisms such as rabbits obtain the carbon necessary for building biological molecules?

B

Rabbits eat plants and break down plant molecules to obtain carbon and other atoms that they rearrange into new carbon-containing molecules.

How would the extra chromosome affect the male offspring produced by the gamete?

C

The male offspring would have full-color vision, because of the presence of the extra X chromosome.

The diploid number of chromosomes in the cell of a domesticated dog is 78. Which of the following options includes the correct number of chromosomes in a cell after each cellular process (G2 checkpoint, meiosis, and fertilization, respectively)?

78-39-78

During prophase I 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?

Scientists have found that DNA methylation suppresses crossing-over in the fungus Ascobolus immersus. Which of the following questions is most appropriately raised by this specific observation?

Responses

A

Is the level of genetic variation in the gametes related to the amount of DNA methylation observed?

Eye color in a particular strain of fly is influenced by one gene with two alleles: a dominant allele that results in red eyes and a recessive allele that results in sepia eyes.

A red-eyed female from a true-breeding population is mated with a sepia-eyed male. The F1 offspring are all red-eyed. The F1 flies are allowed to interbreed, producing the following in the F2 generation.

Females: 40 red eyes; 13 sepia eyes

Males: 39 red eyes; 11 sepia eyes

Which of the following best describes the likely mode of inheritance for the eye-color gene?

A

The eye-color gene is likely autosomal because males and females have similar phenotype ratios.

Which of the following occurs in all species of living organisms and may lead to an increase in genetic variation?

A

Mutations in the genome

Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis I?

C

Each daughter cell contains 12 chromosomes, each composed of two chromatids. Each chromosome is one of a pair of homologous chromosomes from the parent cell, with the other homologue found in the other daughter cell.

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?

D

Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division.

The students calculate a chi-squared value of 92.86 and compare it with a critical value of 7.82. Which of the following best completes the chi-square goodness-of-fit test?

D

The null hypothesis can be rejected, and the students should conclude that the data may have resulted from genetic linkage.

The student calculates a chi-square value of 0.36. Which of the following statements best completes the student's chi-square goodness-of-fit test?

C

The critical value is 3.84, and the student cannot reject the null hypothesis.