AP Bio - Practice Exam #2 MCQ

Which of the following best explains how some cells of an individual proceed and secrete a specific enzyme, but other cells of the same individual do not?

The cells transcribe and translate different combinations of genes, leading to the production go different sets of proteins

A scientist adds a chemical to a culture of dividing cells in order to disrupt DNA replication. The replicated DNA produced by the cells is double-stranded, but sections of it lack covalent bonds between adjacent nucleotides. Which of the following claims is best supported by the data?

The chemical inhibits DNA ligase

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

The chloroplasts will generate less ATP

Beta thalassemia is a disorder caused by mutations in the HBB gene. Examination of the HBB protein in an individual with beta thalassemia shows that the protein is missing many amino acids at its carboxyl terminus. Which of the following is the most likely explanation for how a mutation in the DNA could result in the loss of the carboxyl terminus of the HBB protein?

The mutation changes a codon in the coding region of the HBB transcript to a stop codon such that translation terminates earlier than it should

A researcher observes that when two heterozygous plants with red flowers are crossed, they resulting offspring include plants with red, white, or pink flowers. The researcher proposes the null hypothesis that flower color is the result of independent assortment and incomplete dominance. The researcher calculates a chi-square value of 7.3. Assuming two degrees of freedom, which of the following is the correct interpretation of the chi-square analysis, using a p-value of 0.05?

The null hypothesis should be rejected because the critical value is less than the calculated value

Blood vessels are surrounded by called smooth muscle cells. Nitric oxide triggers a signaling cascade in smooth muscle cells that causes the cells to relax. Which of the following is represented by the gradual increase in thickness of the arrows from the top to the bottom of Figure 1?

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

Based on the pedigrees in Figure 1, which of the following best explains the observed pattern of inheritance?

The trait is an autosomal recessive, because the cross between individuals I-1 and I-2 produced an affected offspring

Goats and sheep belong to the same family but different genera. While they often live together in the same pastures, the hybrid offspring that are occasionally produced between the two species rarely survive. When such a hybrid does survive, it is usually sterile. Which of the following best explains the mechanism that maintains reproductive isolation between goats and sheep?

The two species have a different number of chromosomes, resulting in a post zygotic barrier

The brown anole (Anolis sagrel) is a species of lizard native to Cuba that has been introduced into the southeastern United States. The range of brown anoles in the United States has been expanding, and they are now competing with native green anoles (Anolis carolinensis). Some of the characteristics of the green and brown anoles are shown in Table 1. Based on the data in Table 1, which of the following best explains the observed differences in cold tolerance between brown anoles (A. sagrel) and green anoles (A. carolinensis) in the United States?

Green anoles with greater tolerance for cold had greater reproductive success in areas with colder temperatures

Researchers analyzed the amino acid sequences 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 more distantly related?

Insects and vertebrates

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

pH

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1). Based on the data, which of the following is the best approximation of the rate of growth per week in section II from day 14 to day 21?

4.5 g/week

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of the solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1) In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes in which the membrane is impermeable (nondiffusible solutes) Based on Table 1, which of the following percentages is closest to the solute concentration of the grape?

5.5%

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?

0.02430

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 pH between the control and the treatment group?

35 minutes

A researcher hypothesizes that, in mice, two autosomal dominant traits, trait Q and trait R, are determined by separate genes found on the same chromosome. The researcher crosses mice that are heterozygous for each trait and counts the number of offspring with each combination of phenotypes. The total number of offspring produced was 64. The researcher plans to do a chi-square analysis of the data and calculates the expected number of mice with each combination of phenotypes. which of the following is the expected number of offspring that will display both trait Q and trait R?

36

Poaching is the illegal hunting or capturing of wild animals. Both male and female African elephants have tusks that are a significant source of ivory used for ornaments and jewelry. Assuming that the size of the tusks is heritable, which of the following is the most likely long-term effect of poachers targeting African elephants with large tusks?

A decrease in average tusk size because the elephants with large tusks are less likely to survive to reproduce

Researchers investigated whether time of day affects the rate at which certain mRNAs produced by plants are broken down. At either 1 hour after the start of the light period (morning) or 8 hours after the start of the light period (afternoon), the researchers treated identical plant seedlings with a compound that blocks transcription (time = 0 min). The researchers measured the percent remaining of two mRNAs, mRNA G, and mRNA H over the course of 120 minutes. The data is shown in Figure 1. Based on the data, which of the following best describes the relationship between light and degradation of mRNA G and mRNA H?

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

The brown anole (Anolis sagrel) is a species of lizard native to Cuba that has been introduced into the southeastern United States. The range of brown anoles in the United States has been expanding, and they are now competing with native green anoles (Anolis carolinensis). Some of the characteristics of the green and brown anoles are shown in Table 1. Which of the following is the outgrip in the cladogram shown in Figure 1?

A. carolinensis

Pyruvate kinase, a key enzyme in the glycolysis pathway, is inhibited by the amino acid alanine. The ability of alanine to inhibit the enzyme is not affected by increasing the concentration of substrate. Which of the following best explains the mechanism by which alanine inhibits pyruvate kinase activity?

Alanine binds to an allosteric site of the enzyme, changing the shape of the enzyme's active site

The brown anole (Anolis sagrel) is a species of lizard native to Cuba that has been introduced into the southeastern United States. The range of brown anoles in the United States has been expanding, and they are now competing with native green anoles (Anolis carolinensis). Some of the characteristics of the green and brown anoles are shown in Table 1. Based on Figure 1, which of the following would provide the strongest evidence to support the claim that A. valenclenni and A. lineatopus are the two anole species most closely related to A. sagrei?

Analyzing homologous DNA sequences among the species

A common test for liver function involved sprinkling suffer powder onto a sample of urine (mostly water with dissolved bodily waste). Sulfur powder sprinkled on a sample from an individual with impaired liver function will sink because the urine contains a high level of bile salts, while the sulfur powder sprinkled on normal urine samples will float. Which of the following best explains why bile salts cause the sulfur powder to sink?

Bile salts decrease the surface tension of the urine sample

The brown anole (Anolis sagrel) is a species of lizard native to Cuba that has been introduced into the southeastern United States. The range of brown anoles in the United States has been expanding, and they are now competing with native green anoles (Anolis carolinensis). Some of the characteristics of the green and brown anoles are shown in Table 1. In anoles, small toe pads are better for gripping irregular surfaces such as the forest floor, and large toe pads are better for gripping smooth surfaces such as leaves. Based on the data in Table 1, if brown anoles are introduced into a forest where green anoles currently live, which of the following predictions about the two species is most likely?

Brown anoles will occupy a different area of the forest green from green anoles which will minimize competition

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?

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

The brown anole (Anolis sagrel) is a species of lizard native to Cuba that has been introduced into the southeastern United States. The range of brown anoles in the United States has been expanding, and they are now competing with native green anoles (Anolis carolinensis). Some of the characteristics of the green and brown anoles are shown in Table 1. Based on the cladogram in Figure 1, which of the following conclusions about the evolution of the anole species is most reasonable?

Each species evolved as a result of different selective pressures

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1). Which of the following best explains the connection between energy, growth, and maintenance of an ordered system in the experiment?

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

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

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

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 is shown in the table Which of the following samples most likely contains a double-stranded RNA virus?

Sample 1

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, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts. The Esp 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 Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts (Figure 2). Which of the following claims is most consistent with the data shown in Figure 2?

Esp expression is necessary to prevent the overproduction of insulin

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of the solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1) In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes in which the membrane is impermeable (nondiffusible solutes) Based on Table 1, which of the following best explains the difference in water potential between certain solutions and the grapes?

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

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, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts. The Esp 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 Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts (Figure 2). Which of the following best describes the effect of insulin binding to the receptor on the osteoblast cells?

Insulin binding ultimately increases pancreatic secretion of additional insulin

Based on the data in Figure 1, which of the following most likely represents the change in energy that occurs when ATP hydrolysis is coupled with the phosphorylation of a substrate?

Line 1 represents ATP hydrolysis, and line 4 represents phosphorylation of a substrate

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1). Which of the following best explains the observed differences in mass between the grass in section I after 14 days and the grass in section III after 21 days?

Mass lost by cell respiration in section III was not replaced by photosynthesis

The human sleep-wake cycle is regulated by melatonin. The synthesis of melatonin is regulated by light exposure (Figure 1). The human body typically develops a sleep-wake rhythm that does not respond quickly to change. Long term exposure to extended periods of bright light after sunset is most likely to affect a person in which of the following ways?

Melatonin synthesis inhibited, and the person will have difficulty sleeping

The amino acid in Figure 1 is found in a region of a polypeptide that folds away from water. Which part of the amino acid most likely contributes to the hydrophobic behavior of this region of the polypeptide?

Methyl (CH2) group

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

Mitochondria have their own DNA and divide independently of the cell

A typical bag of fertilizer contains high levels of nitrogen, phosphorous, and potassium but trace amounts of magnesium and calcium. Which of the following best matches the fertilizer component with the molecule in which it will be incorporated by organisms in the area?

Nitrogen will be incorporated into nucleic acids

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, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts. The Esp 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 Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts. Which of the following was a positive control in the experiment?

Normal strain

Which of the following best describes a characteristic of DNA that makes it useful as hereditary material?

Nucleotide bases in one strand can only be paired with specific bases in the other strand

Which of the following best explains how continuity of genetic information in cells is ensured across generations?

Replication uses a parental strand of DNA as a template to create a new strand of DNA

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of the solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1) In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes in which the membrane is impermeable (nondiffusible solutes) 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)?

Small diffusible solutes will diffuse into the grape soda, followed by water

Which of the following best describes the hydrolysis of carbohydrates?

The addition of a water molecule breaks a covalent bone between sugar monomers

Which of the following best describes the process by which the bacteria are breaking down the glucose to produce lactic acid?

The bacteria are breaking down sugars in the absence of oxygen

Different species of bumblebee compete for flower nectar in their ecosystem. While the flowers vary in the length of their petals, bumblebees vary in the length of a mouth part called a proboscis. Bumblebees demonstrate a preference for flowers that correspond to the length of the proboscis. Species with proboscises of similar length tend to occupy different areas. Species that live in the same area tend to have proboscises of different lengths. which of the following best explains the relationship between the different bumblebee species living in the same area?

The bumblebees have undergone niche partitioning due to competition

Which of the following most likely explains how the chromosomes circles in Figure 1 could cause a genetic disorder in the person from which the cells were obtained?

The extra chromosome will affect the levels of RNA transcribed from certain genes and the amount of protein produced from those genes in each cell

Mercurial sulfhydryl is an inhibitor or aquaporins. Which of the following is the most likely effect of adding mercurial sulfhydryl to the distilled water molecule?

The grape cells will gain water more slowly because of a lack of facilitated diffusion

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of the solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1) In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes in which the membrane is impermeable (nondiffusible solutes) Based on the data in Table 1, which of the following best evaluates the student's hypothesis?

The hypothesis is not supported because the mass of the grape increased in the grape juice

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, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts. The Esp 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 Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts (Figure 2) Based on the information provided, which of the following best justifies the claim that osteocalcin is a hormone?

The osteoblasts in the bone secrete osteocalcin in the pancreas to change their activity

According to the data, which of the following best explains the results of the experiment?

The pH of the treatment culture was lower than the pH of the control because the chemical increased the bacterial metabolic rate

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, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts. The Esp 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 Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts. A researcher observes that mice from the mutant strain experience low blood sugar. Which of the following best describes the feedback mechanism in the pathway (Figure 1) causing the low blood sugar in the mutant strain?

The positive feedback of insulin production

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1). Which of the following is a approximate null hypothesis for the student's experiment?

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

Which of the following best explains how the expression of a eukaryotic gene encoding a protein will differ if the gene is expressed in a prokaryotic cell instead of in a eukaryotic cell?

The protein will be made but will not function because prokaryotes cannot remove introns

Figure 1 shows the amount of product produced in an enzyme-catalyzed reaction over five minutes. Which of the following best explains how the rate of the reaction changes over time?

The rate decreases because the ratio of product to substrate increases

Which of the following best explains why larger grapes have a different rate of water absorption per gram of mass than smaller grapes do?

The rate is slower because smaller grapes have a larger surface-area-to-volume ratio than the larger grapes do

Pitcher plants are carnivorous plants that grow in areas where the soil contains low levels of key nutrient such as nitrogen. To obtain these nutrients, most pitcher plants capture prey using traps containing a digestive fluid. The captured prey are then broken down and digested, and the pitcher plant absorbs the nutrients. The traps of one species of pitcher plant, Nepenthes hemsleyana, do not contain digestive fluid. Instead the provide a suitable place for wooly bats (Kerivoula hardwicki) to sleep. The feces from the bat are released into the trap where nutrients in the feces are absorbed and provide the plant with the nitrogen it needs. Which of the following best describes the relationship between the pitcher plant and the wooly bat?

The relationship is mutualistic because both the plant and the bat benefit

A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a non polar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has much lower activity than the normal enzyme does. Which of the following most likely explains how the amino acid substitution has resulted in decreased catalytic activist by the mutated enzyme?

The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1). Based on the data, which of the following is the most likely effect of a period of increased volcanic activity that significantly decreases the amount go sunlight reaching a particular ecosystem for several years?

There will be a decrease in the population sizes of most species and a decrease in the number of trophic levels

Low concentrations of cadmium in the water negatively affect steelhead trout. In a river community, steelhead trout are part of the trophic structure shown in Figure 1. Which of the following is the most likely immediate effect of an increase in runoff containing cadmium on the trophic structure of the river community?

There will be a large decrease in the trout population, resulting in an increase in damselfly nymphs

Which of the following observations would best provide the strongest evidence that two plants belong to different biological species?

They produce viable but sterile offspring