AP Bio: Multiple Choice Practice Questions (From old tests)
Gaucher disease type I (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 the Hardy-Weinberg equilibrium, calculate the frequency of the wild-type (nonmutant) allele for the enzyme glucocerebrosidase?
0.967
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (nontaster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the nontaster allele The nucleotides present at the three positions are shown in the table below. In a sample of 2400 people, 1482 were found to have the dominant (taster) phenotype. Assuming that the population is in the Hardy-Weinberg equilibrium, approximately how many individuals in the sample are expected to be heterozygous for TAS2R38 gene?
918
Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in the initiation of a cancerous tumor?
A defect in a cell-cycle checkpoint prevents a cell from entering the S phase
The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway?
A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger
One of the oldest known mammalian fossils belongs to a small furry species, Hadrocodium wui, that lived 195 million years ago. For the following 100 million years, only a small number of groups of mammalian fossils are found in the fossil record. By 65 million years ago, the nonavian dinosaurs were extinct. By 55 million years ago, there were 130 mammal genera, including 4,000 different species that occupied a wide variety of habitats. 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?
After the dinosaur extinction, many ecological niches became available, leading to the adaptive radiation of mammals
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (nontaster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the nontaster allele The nucleotides present at the three positions are shown in the table below. Which of the following conclusions is supported by the data?
Bonobos are more closely related to humans than to gorillas because bonobos and humans share a more recent common ancestor than bonobos and gorillas do
Glycogen synthase 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 synthase kinase 3 beta (GSK 3B) can act either as an oncogene or as a tumor suppressor. Which of the following best predicts how GSK 3B mutations can lead to the development of cancer?
Cells with overactive GSK 3B are more likely to repair DNA damage
Lobe-finned fished were present in the oceans of the world approximately 400 million years ago. the first tetrapods (vertebrates that had limbs and could move on land) appeared about 365 million years ago. One hypothesis states that early tetrapods evolved from lobe-finned fishes. Which of the following is the best plan for testing the hypothesis?
Comparing the arrangement of bones in the fins of lobe-finned fishes and limbs of the earliest tetrapods
Notch is a receptor protein displayed on the surface of certain cells in developing fruit fly embryos. Notch's ligand is a membrane-bound protein called Delta that is displayed on the surface of adjacent cells. When Notch is activated by its ligand, the intracellular tail of the Notch protein becomes separated from the rest of the protein. This allows the intracellular tail to move to the cell's nucleus and alter the expression of specific genes. Which of the following statements best explains Delta's role in regulating cell communication through the Notch signaling pathway?
Delta restricts cell communication to a short distances within a developing embryo
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (nontaster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the nontaster allele The nucleotides present at the three positions are shown in the table below. Which of the following scientific questions will best help researchers determine when the nontaster allele arose in the evolutionary history of the selected primates?
Does the nontaster allele exist in any nonhuman primate populations?
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 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 statements might best explain the increase in the average beak size in the finch population during the drought?
Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring
Which of the following pieces of evidence best supports the hypothesis that birds and crocodilians (crocodiles and alligators) are more closely related to each other than they are to other organisms?
Fossil evidence indicates that both modern birds and crocodilians originated during the Jurassic Period
A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following statements best helps justify the researchers claim?
Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phospate
In a certain signal transduction pathway, the binding of an extracellular molecule to a cell-surface protein results in a rapid increase in the concentration of cyclic AMP inside the cell. The cyclic AMP binds to and activates cytosolic enzymes that then activate other enzymes in the cell. Which of the following statements best describes the role of cyclic AMP in the signal transduction pathway?
It acts as a second messenger that helps relay and amplify the signal within the cell
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?
Loss-of-function mutations in ethylene receptors result in changes to the ripening process
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?
Small, water-soluble molecules
Malaria is a caused by several different species of Plasmodium, a protozoan parasite. Plasmodium resistance to common drugs used to treat malaria has increased in recent years. In a scientific study, Plasmodium samples were analyzed in blood drawn from a large number of infected patients before drug treatment and subsequently from the subset of infected patients with drug-resistant Plasmodium. DNA sequences of four different Plasmodium genes thought to be involved in resistance were compared between samples from patients with drug sensitive Plasmodium and patients with drug-resistant Plasmodium. Which of the following best supports the hypothesis that preexisting mutations confer drug resistance?
Some of the mutations that occur most frequently in samples from patients treated with antimaterial drugs are detectable in Plasmodium samples collected prior to use of antimalarial drugs
The California newt, Taricha torosa, lives in the coastal areas around Los Angeles. Which of the following is a valid null hypothesis relating relative fitness to survival of a bottleneck event in a coastal area where a small, isolated population of California newts resides?
Surviving the bottleneck event will be random, so any change in allelic frequencies of the salamander population is not attributed to fitness
A student claims that the Y chromosome contains the sex-determining region gene, known as the SRY gene, which causes male fetuses to develop testes. Which of the following provides correct information about cell signaling that supports the claim?
The SRY gene produces a protein that binds to specific regions of DNA in certain tissues, which affects the development of these tissues
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?
The eye-color gene is likely autosomal because males and females have similar phenotype ratios
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 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 best describes the mechanism behind the change in beak size in the finch population?
The formation of the two new finch species from a single parent species
Which of the following statements best describes how a growth factor stimulates cell division from outside the cell?
The growth factor binds to receptors on the cell surface, initiating a signal transduction pathway that activates specific target genes
Which of the following outcomes will most likely result from the irreversible binding of GDP to the G protein?
The intracellular concentration of glycogen will increase
Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHC proteins and T cell receptors, mediate cell communication over short distances?
The proteins interact directly with proteins on the surfaces of other cells
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?
The temperatures and pressure found in the hydrothermal vents resemble conditions described in currently accepted origins of life hypotheses
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's usually sterile. Which of the following best explains the mechanism that maintains a reproductive isolation between goats and sheep?
The two species have a different number of chromosomes, resulting in a postzygotic barrier
In humans, one allele of the APOE gene, called APOE-ε2, can result in a high tolerance of cholesterol. Cholesterol is a vital substance for humans but may lead to heart disease in an older adult with a history of high cholesterol diets. High cholesterol diets are becoming more prevalent in the United States. Currently only about 2% of humans carry the APOE-ε2 allele. Which of the following states a valid null hypothesis about the future distribution of APOE alleles in future generations in the United States?
The variant protects an individual from a condition that is only common among humans beyond reproductive age, so the frequency of the allele will likely not change in the future because it is not influenced by natural selection
The hormone prolactin has varying effects in many different animal species. All vertebrates produce prolactin, which is involved in signal transduction pathways. In mammals, prolactin stimulates the production of milk in mammary glands. In fish, prolactin plays an important role in osmoregulation. In birds, prolactin is involved in lipid metabolism. Which of the following best explains the presence of prolactin in various species?
Though all vertebrates produce prolactin , its varied uses indicate it arose as a result of convergent evolution and not as a result of common ancestry.
