AP Biology Exam
Strenuous exercise lowers the blood pH, causing the curves for both hemoglobin and myoglobin to shift to the right. This shift results in
(A) an unloading of O2 at higher partial pressures
Plates I and III were included in the experimental design in order to
(A) demonstrate that the E. coli cultures were viable
According to the results of this experiment, germination of tobacco seeds during the first week is
(A) increased by exposure to light
An individual's humoral response to a particular antigen differs depending on whether or not the individual has been previously exposed to that antigen. Which of the following graphs properly represents the humoral immune response when an individual is exposed to the same antigen more than once?
(A)
Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide?
(A)
Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. (The formula for the surface area of a cube is 6 x S^2, and the formula for the volume of a cube is S^3, where S= the length of a side of the cube.) Which of the following cube-shaped cells would be most efficient in removing waste by diffusion?
(A) 10 um
The diagram above shows a developing worm embryo at the four-cell stage. Experiments have shown that when cell 3 divides, the anterior daughter cell gives rise to muscle and gonads and the posterior daughter cell gives rise to the intestine. However, if the cells of the embryo are separated from one another early during the four-cell stage, no intestine will form. Other experiments have shown that if cell 3 and cell 4 are recombined after the initial separation, the posterior daughter cell of cell 3 will once again give rise to normal intestine. Which of the following is the most plausible explanation for these findings?
(A) A cell surface protein on cell 4 signals cell 3 to induce formation of the worm's intestine.
During aerobic cellular respiration, oxygen gas is consumed at the same rate as carbon dioxide gas is produced. In order to provide accurate volumetric measurements of oxygen gas consumption, the experimental setup should include which of the following?
(A) A substance that removes carbon dioxide gas
The first diagram below shows the levels of mRNA from two different genes (bicoid and caudal) at different positions along the anterior-posterior axis of a Drosophila egg immediately before fertilization. The second diagram shows the levels of the two corresponding proteins along the anterior-posterior axis shortly after fertilization. Which of the following conclusions is best supported by the data?
(A) Bicoid protein inhibits translation of caudal mRNA.
The figures below illustrate the similarities between ATP synthesis in mitochondria and chloroplasts.
(A) Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?
The diagram above shows the progression of ecological events after a fire in a particular ecosystem. Based on the diagram, which of the following best explains why the oak trees are later replaced by other trees?
(A) Eventually the other trees grow taller than the oak trees and form a dense canopy that shades the understory.
Which of the following statements might best explain the increase in average beak size in the finch population during the drought?
(A) Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring
Anabaena is a simple multicellular photosynthetic cyanobacterium. In the absence of fixed nitrogen, certain newly developing cells along a filament express genes that code for nitrogen-fixing enzymes and become non-photosynthetic heterocysts. The specialization is advantageous because some nitrogen-fixing enzymes function best in the absence of oxygen. Heterocysts do not carry out photosynthesis but instead provide adjacent cells with fixed nitrogen, in exchange receiving fixed carbon and reduced energy carriers. As shown in the diagram above, when there is low fixed nitrogen in the environment, an increase in the concentration of free calcium ions and 2-oxyglutarate stimulates the expression of genes that produce two transcription factors (NtcA and HetR) that promote the expression of genes responsible for heterocyst development. HetR also causes production of a signal, PatS, that prevents adjacent cells from developing as heterocysts. Based on your understanding of the ways in which signal transmission mediates cell function, which of the following predictions is most consistent with the information given above?
(A) In an environment with low fixed nitrogen, treating the Anabaena cells with a calcium-binding compound should prevent heterocyst differentiation.
The area covered by tropical rain forest is reduced by millions of hectares per year due to agriculture and logging. Which of the following best describes a likely result of tropical rain forest deforestation?
(A) Populations of plants and animals will decrease as more rain forest disappears, leading to a decrease in biodiversity.
Arctic foxes typically have a white coat in the winter. In summer, when there is no snow on the ground, the foxes typically have a darker coat. Which of the following is most likely responsible for the seasonal change in coat color?
(A) The decrease in the amount of daylight in winter causes a change in gene expression, which results in the foxes growing a lighter-appearing coat.
Which of the following best explains why there is no growth on plate II?
(A) The initial E. coli culture was not ampicillin-resistant
According to the data, the mice at 10 degrees Celsius demonstrated greater oxygen consumption per gram of tissue than did the mice at 25 degrees Celsius. This is most likely explained by which of the following statements?
(A) The mice at 10 degrees Celsius had a higher rate of ATP production than the mice at 25degrees Celsius.
Which of the following can best be used to justify why the GFP is expressed by E. coli cells after transformation with the plasmid?
(A) The presence of arabinose in the nutrient agar activated the expression of the genes located downstream of the ara-operon regulatory sequences.
Sickle-cell anemia results from a point mutation in the HBB gene. The mutation results in the replacement of an amino acid that has a hydrophilic R-group with an amino acid that has a hydrophobic R-group on the exterior of the hemoglobin protein. Such a mutation would most likely result in altered
(A) properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules
A culture of Spirogyra (an autotrophic alga) is maintained in a water solution containing dissolved carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher determines the rates of synthesis of several organic compounds found in the Spirogyra before and after several weeks in the water solution. Which of the following graphs best illustrates a likely result of the experiment?
(B)
Which of the following best describes the mechanism behind the change in beak size in the finch population?
(B) A change in gene frequencies in the finch population due to selective pressure from the environmental change
The illustration above depicts a neuromuscular junction of a patient with an autoimmune disorder. Acetylcholine is a stimulatory neurotransmitter. Which of the following would be the most likely result of the continued presence of the antibody?
(B) A decrease in action potentials in the muscle, causing muscle weakness and fatigue
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?
(B) A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger.
The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system?
(B) After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels.
A group of students summarized information on five great extinction events. The students are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following would be the most reasonable plan for the students to follow?
(B) Collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones
The chemical reaction for photosynthesis is 6 CO2 + 12 H2O + light energy --> C6H12O6 + 6 O2 + 6 H2O. If the input water is labeled with a radioactive isotope of oxygen (18)O, then the oxygen gas released as the reaction proceeds is also labeled with (18)O. Which of the following is the most likely explanation?
(B) During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released
The most probable cause for the difference in mean stem length between plants in dish A and plants in dish B is which of the following?
(B) Elongation of seedlings in response to the lack of light
Testosterone oxido-reductase is a liver enzyme that regulates testosterone levels in alligators. One study compared testosterone oxido-reductase activity between male and female alligators from Lake Woodruff, a relatively pristine environment, and from Lake Apopka, an area that has suffered severe contamination. The graph above depicts the findings of that study. The data in the graph best support which of the following claims
(B) Environmental contamination reduces total testosterone oxido-reductase activity in females.
Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms from all three domains, Archaea, Bacteria, and Eukarya. Which of the following hypotheses could be best supported by this evidence?
(B) Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life.
Which of the following statements best explains why there are fewer colonies on plate IV than on plate III?
(B) Not all E. coli cells are successfully transformed
The following is a food web for a meadow habitat that occupies 25.6 km^2 . The primary producers' biomass is uniformly distributed throughout the habitat and totals 1,500 kg/km^2. Developers have approved a project that will permanently reduce the primary producers' biomass by 50 percent and remove all rabbits and deer. 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 of the following statements best supports the claim that organisms share fundamental processes as a result of evolution?
(C) All organisms share a genetic code organized into triplet codons, making it possible for one organism to express a gene from another organism.
Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation for the data?
(B) The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.
In most freshwater fish, nitrogenous waste is primarily excreted as ammonia, which is highly soluble in water and is toxic at low concentrations. In terrestrial mammals, ammonia is converted to urea before it is excreted. Urea is also highly soluble in water but is less toxic than ammonia at low concentrations. Which of the following best explains why freshwater fish do not convert ammonia to urea for excretion?
(B) The dilution of ammonia by direct excretion into freshwater conserves energy.
The biologist discovered that from 1988 to 1993, the average beak size declined to pre-1981 levels. The reversal in beak size from 1988 to 1993 was most likely related to which of the following events?
(B) The end of the drought
During the infection cycle for a typical retrovirus, such as HIV, which uses RNA as genetic material, the genetic variation in the resulting population of new virus particles is very high because of
(B) errors introduced in the DNA molecule through reverse transcription
A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?
(C)
Figure I shows the growth of an algal species in a flask of sterilized pond water. If phosphate is added as indicated, the growth curve changes as shown in Figure II. Which of the following is the best prediction of the algal growth if nitrate is added instead of phosphate?
(C)
Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of rRNA subunits were determined for the new species. The table below shows the number of nucleotide differences between the species. Which of the following phylogenetic trees is most consistent with the data?
(C)
Both myoglobin and hemoglobin are proteins that bind reversibly with molecular oxygen. The graph below shows the oxygen-binding saturation of each protein at different concentrations of oxygen. Which of the following statements is correct?
(C) At 40 mm Hg partial pressure, myoglobin has a greater affinity for oxygen than hemoglobin has
In a second experiment, the plasmid contained the gene for human insulin as well as the ampr gene. Which of the following plates would have the highest percentage of bacteria that are expected to produce insulin?
(C) IV only
Plates that have only ampicillin-resistant bacteria growing include which of the following?
(C) IV only
Membrane-bound organelles have been an important component in the evolution of complex, multicellular organisms. Which of the following best summarizes an advantage of eukaryotic cells having internal membranes?
(C) Organelles isolate specific reactions, increasing metabolic efficiency.
The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these two segments would differ?
(C) Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three
Which of the following procedures was most likely followed to determine the change in beak size?
(C) The beak size in a large number of finches was measured every year from 1981 to 1987.
By discharging electric sparks into a laboratory chamber atmosphere that consisted of water vapor, hydrogen gas, methane, and ammonia, Stanley Miller obtained data that showed that a number of organic molecules, including many amino acids, could be synthesized. Miller was attempting to model early Earth conditions as understood in the 1950s. The results of Miller's experiments best support which of the following hypotheses?
(C) The molecules essential to life today could have formed under early Earth conditions
MRSA is the acronym for methicillin-resistant Staphylococcus aureus. Many of the strains of the common bacterium are also resistant to other antibiotics in use today. The resistance is linked to a collection of genes carried on plasmids that are passed from one bacterium to another by conjugation. Suppose a newly discovered, chemically different antibiotic is used in place of methicillin. Which of the following would be the most likely effect on Staphylococcus aureus antibiotic resistance?
(C) Transmission of the methicillin-resistance plasmid would gradually decrease but the plasmid would not entirely disappear from the Staphylococcus aureus population.
The Hedgehog protein (Hh) plays a critical role during a certain period of embryo development, but it normally has no role in adults except for the maintenance of adult stem cells. However, the Hedgehog protein has been detected in 70 percent of pancreatic cancer cell samples. As illustrated in the figures below, the Hedgehog protein binds to an integral membrane protein receptor known as Patched (Ptc), thus initiating a pathway of gene expression. When Hedgehog is absent, Ptc inhibits another protein known as Smoothened (Smo), which, in turn, blocks the activation of a group of proteins collectively known as the Hedgehog signaling complex (HSC). The inactivation is the result of proteolytic cleavage of one component of the HSC complex, a transcription factor known as Cubitus interruptus (Ci). When Hedgehog is present, it binds to Ptc, which prevents the inhibition of Smo by Ptc. The result is that Ci remains intact and can enter the nucleus, where it binds to and activates certain genes. One approach to treating patients with pancreatic cancer and other cancers in which the Hedgehog protein is detected is to modify the Hedgehog signaling pathway. Which of the following is the most useful approach?
(C) Treating patients with a membrane-soluble com pound that can bind to Smo and block its activity
The FtsZ protein is present in prokaryotes and in chloroplasts. The protein is structurally and functionally similar to tubulin proteins of eukaryotic cells. Which of the following is a likely conclusion to draw from this information?
(C) Tubulin genes are evolutionarily derived from the gene that codes for the FtsZ protein.
A sample of human blood was placed in a test tube containing a physiological saline solution (0.9% sodium chloride). This type of solution is often used intravenously to quickly rehydrate patients. A drop of the blood from the test tube was placed on a slide and red blood cells (RBCs) were observed under a microscope. Three possible outcomes are diagrammed below. Which of the following best predicts which diagrammed microscope view the laboratory worker would see and best explains why?
(C) View 2 because the rate of water movement into the RBCs equals the rate of water movement out of the cells
The last part of the metamorphosis of a tadpole to an adult frog results in the disappearance of the tail. This stage of development most likely occurs by
(C) bilateral division of the tail and fusion with the developing hind limbs
According to the data, the crickets at 25 degrees Celsius have greater oxygen consumption per gram of tissue than do the crickets at 10 degrees Celsius. This trend in oxygen consumption is the opposite of that in the mice. The difference in trends in oxygen consumption among crickets and mice is due to their
(C) mode of internal temperature regulation
Additional observations were made on day 21, and no yellow-leaved seedlings were found alive in either dish. This is most likely because
(C) yellow-leaved seedlings were unable to convert light energy to chemical energy
Lactose digestion in E. coli begins with its hydrolysis by the enzyme B-galactosidase. The gene encoding B-galactosidase, lacZ, is part of a coordinately regulated operon containing other genes required for lactose utilization. Which of the following figures correctly depicts the interactions at the lac operon when lactose is NOT being utilized?
(D)
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)
The figure above shows several steps in the process of bacteriophage transduction in bacteria. Which of the following explains how genetic variation in a population of bacteria results from this process?
(D) DNA of the recipient bacterial chromosome under goes recombination with DNA introduced by the phage from the donor bacterium, leading to a change in the recipient's genotype.
Living cells typically have biosynthetic pathways to synthesize at least some of the amino acids used in making proteins. Some strains of E. coli, a prokaryote, can synthesize the amino acid tryptophan, while other E. coli strains cannot.Similarly, some strains of the yeast S. cerevisiae, a eukaryote, can synthesize tryptophan, while other S. cerevisiae strains cannot. Which of the following describes the most likely source of genetic variation found in the tryptophan synthesis pathways of both species?
(D) Errors in DNA replication lead to genetic variation.
The tiny blue-eyed Mary flower is often one of the first flowers seen in the spring in some regions of the United States. The flower is normally blue, but sometimes a white or pink flower variation is found. The following data were after several crosses. Which of the following statements best explains the data?
(D) Flower color is an inherited trait, and the F1 and F2 phenotypes of the flowers arising from the pink and white cross can best be explained by another gene product that influences the phenotypic expression.
Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis?
(D) Plants generally use starch molecules for storage while animals use glycogen and fats for storage.
In a hypothetical population of beetles, there is a wide variety of color, matching the range of coloration of the tree trunks on which the beetles hide from predators. The graphs below illustrate four possible changes to the beetle population as a result of a change in the environment due to pollution that darkened the tree trunks.Which of the following includes the most likely change in the coloration of the beetle population after pollution and a correct rationale for the change?
(D) The coloration in the population shifted toward more darker-colored beetles, as in diagram IV. The lighter- colored beetles were found more easily by the predators than were the darker-colored beetles
Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled?
(D) The existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
A human kidney filters about 200 liters of blood each day. Approximately two liters of liquid and nutrient waste are excreted as urine. The remaining fluid and dissolved substances are reabsorbed and continue to circulate throughout the body. Antidiuretic hormone (ADH) is secreted in response to reduced plasma volume. ADH targets the collecting ducts in the kidney, stimulating the insertion of aquaporins into their plasma membranes and an increased reabsorption of water.
(D) The person would produce greater amounts of dilute urine.
Which of the following best describes the physiological significance of the different oxygen-binding capabilities of hemoglobin and myoglobin?
(D) They enhance movement of oxygen from the blood into the muscles.
