AP Biology Exam Review PDF
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This is an AP Biology past paper. The document outlines multiple choice questions and free-response questions centered around topics including enzyme activity and the effects of environmental conditions, such as pH, on enzyme function. The format suggests a review or practice exam.
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AP BIOLOGY Scoring Guide Unit 3 Progress Check: MCQ Researchers investigated the influence of environmental on the activity of peroxidase, an enzyme that catalyzes the conversion of hydrogen peroxide to water and oxygen gas. In an experiment, the res...
AP BIOLOGY Scoring Guide Unit 3 Progress Check: MCQ Researchers investigated the influence of environmental on the activity of peroxidase, an enzyme that catalyzes the conversion of hydrogen peroxide to water and oxygen gas. In an experiment, the researchers added a hydrogen peroxide solution containing guaiacol to several identical test tubes and adjusted the solution in each test tube to a different. The researchers included the guaiacol because it caused the solutions to change color as the reactions proceeded, which the researchers relied on for measuring reaction rates. Finally, the researchers added the same amount of peroxidase to each test tube and measured the rate of each reaction at. The results of the experiment are represented in Figure 1. Figure 1. The effect of on peroxidase activity 1. Based on Figure 1, which of the following statements best predicts the effect that a change from a moderately acidic environment ( near 6) to a basic environment will have on peroxidase activity? (A) Peroxidase activity will decrease. (B) Peroxidase activity will increase. (C) Peroxidase activity will stay the same. (D) Peroxidase activity will increase at first and then decrease. Answer A Correct. Based on Figure 1, peroxidase’s optimal is 5. A change from a moderately acidic environment ( near 6) to a basic environment ( above 7) will result in a decrease in peroxidase activity. 2. Which of the following actions will provide a negative control for the investigation? (A) Repeating the experiment at (B) Repeating the experiment using twice the amount of hydrogen peroxide (C) Repeating the experiment using twice the amount of peroxidase (D) Repeating the experiment using heat-denatured peroxidase AP Biology Page 1 of 18 Scoring Guide Unit 3 Progress Check: MCQ Answer D Correct. A negative control is a group in which no response is expected. It is the opposite of the positive control, in which a known response is expected. Heat-denatured peroxidase will be inactive. Repeating the experiment using heat-denatured peroxidase will allow the researcher to measure reaction rates in the presence of inactive peroxidase. 3. One of the researchers proposes using oxygen gas production to measure reaction rates. Which of the following statements best justifies the use of the proposed modification as a way of creating an appropriate control for the investigation? The experiment can be repeated without hydrogen peroxide, which will help eliminate an uncontrolled (A) variable. The experiment can be repeated without peroxidase, which will introduce a second independent (B) variable. The experiment can be repeated without guaiacol, which will reveal the effect of guaiacol on the (C) reaction rates. The experiment can be repeated without water, which will reveal whether the reaction can occur inside a (D) living cell. Answer C Correct. In the original experiment, the researchers used guaiacol as a reaction indicator. By using oxygen gas production to measure reaction rates, the researchers no longer need the guaiacol and can repeat the experiment without it, which will reveal the effect of guaiacol on the reaction rates. 4. Aminolevulinate dehydratase ( ) is an enzyme that relies on zinc as a cofactor. A zinc ion binds to the active site, where it forms favorable interactions with the side chains of three amino acids. Researchers have found that substituting a lead ion for a zinc ion in the active site causes inhibition of. Which of the following statements best helps explain how the lead ion causes inhibition of ? It changes the shape and charge of the substrate so that it becomes more compatible with ’s (A) active site. It changes the amino acid sequence of the protein so that the enzyme catalyzes a different (B) reaction. It changes the three-dimensional structure of the active site so that is no longer compatible with (C) its substrate. It changes the enzyme-substrate complex so that the transition state is more stable and the reaction (D) proceeds at a faster rate. Page 2 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ Answer C Correct. The substitution of a lead ion for a zinc ion most likely changes the three-dimensional structure of the active site. The three-dimensional structure of the active site plays an important role in the compatibility between an enzyme and its substrate. Changing the structure of the active site will likely interfere with enzyme function by disrupting the enzyme-substrate interaction. 5. Acetylcholinesterase is a protein that catalyzes the conversion of acetylcholine to acetate and choline. When the concentration of in an aqueous solution is held constant, the rate of the reaction catalyzed by increases with increasing concentrations of substrate. At low concentrations of acetylcholine, a small increase in the substrate concentration results in a large increase in the reaction rate. At high concentrations of acetylcholine, however, a large increase in the substrate concentration results in only a small increase in the reaction rate. Which of the following statements correctly explains the observed effect of the acetylcholine concentration on the rate of the enzyme-catalyzed reaction? The active site of is specific for acetylcholine, and only one substrate molecule can occupy the (A) active site at a time. begins converting product into substrate as the acetylcholine concentration changes from low to (B) high. (C) The protein becomes denatured as the acetylcholine concentration changes from low to high. The substrate specificity of changes as the acetylcholine concentration changes from low to (D) high. Answer A Correct. Acetylcholine is the substrate for , and since the shape and charge of the active site is specific for acetylcholine, only one substrate molecule can occupy the active site at a time. Therefore, at high concentrations of acetylcholine, becomes saturated with substrate. When an enzyme is saturated with substrate, adding more substrate to the solution will not lead to an observable increase in the reaction rate. 6. A researcher proposes a model to explain how enzyme-substrate interactions determine enzyme specificity. The model is based on the idea that substrate molecules form favorable interactions with the amino acid side chains in an enzyme’s active site. Based on the model, which of the following statements best explains an enzyme’s specificity for a particular substrate molecule? AP Biology Page 3 of 18 Scoring Guide Unit 3 Progress Check: MCQ (A) A hydrophilic molecule interacts with nonpolar side chains in the enzyme’s active site. (B) A hydrophobic molecule interacts with polar side chains in the enzyme’s active site. A molecule with positive charges interacts with positively charged side chains in the enzyme’s active (C) site. A molecule with negative charges interacts with positively charged side chains in the enzyme’s active (D) site. Answer D Correct. Because opposite charges attract, a molecule with negative charges will form favorable interactions with positively charged side chains in an enzyme’s active site. Based on the model, the favorable interactions helps explain the enzyme’s specificity for the molecule as a substrate. 7. Catalase is an enzyme found in yeast cells that facilitates the chemical breakdown of hydrogen peroxide to water and oxygen gas. An experiment was conducted to determine the effect of on catalase function. Five buffer solutions of varying (2, 4, 6, 8, and 10) were prepared and added to separate test tubes. Hydrogen peroxide was added to each test tube. Yeast was added, and the reactions were timed. After 1 minute the amount of oxygen gas released was determined by measuring the foam layer produced in each test tube. Figure 1 illustrates the experimental setup. Figure 1. Illustration of experimental procedure A set of five additional test tubes were prepared and used as controls. Which of the following best describes the contents expected to be contained in one of the five control test tubes? Page 4 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ (A) 4 buffer solution and hydrogen peroxide only (B) All five buffer solutions combined and hydrogen peroxide only (C) Water, hydrogen peroxide, and yeast (D) Water and yeast only Answer A Correct. Since the experiment is studying the effect of on catalase in yeast, the control set should determine what would happen without yeast present. Each test tube in the control set should contain hydrogen peroxide and one of the solutions. 8. A student designs an experiment to investigate the influence of temperature on enzyme function. The student’s plan is presented in Table 1. Table 1. An experiment to investigate the influence of temperature on enzyme function Test Tube Substrate Added Enzyme Added Temperature 1 Yes No 10 2 Yes Yes 10 3 Yes No 20 4 Yes Yes 20 5 Yes No 30 6 Yes Yes 30 7 Yes No 40 8 Yes Yes 40 Which test tubes are controls in the experiment? (A) Test tubes 1 and 2 only (B) Test tubes 5 and 6 only (C) Test tubes 1, 3, 5, and 7 (D) Test tubes 2, 4, 6, and 8 AP Biology Page 5 of 18 Scoring Guide Unit 3 Progress Check: MCQ Answer C Correct. The test tubes that do not contain the enzyme are negative controls in the experiment. The negative controls help confirm that the results of the experiment are related to enzyme function and not some other factor. 9. A researcher designs an experiment to investigate whether soil bacteria trigger the synthesis of defense enzymes in plant roots. The design of the experiment is presented in Table 1. For each group in the experiment, the researcher will determine the average rate of change in the amount of defense enzymes in the roots of the seedlings. Table 1. An experiment to investigate the effect of soil bacteria on plant defenses Group Number of Seedlings Type of Soil Treatment Solution 1 10 Sterile potting soil Contains actively reproducing soil bacteria 2 10 Sterile potting soil Contains heat-killed soil bacteria 3 10 Sterile potting soil Contains no soil bacteria Which of the following statements best helps justify the inclusion of group 2 as one of the controls in the experiment? (A) It will show whether the changes observed in group 1 depend on the metabolic activity of soil bacteria. It will show whether the changes observed in group 1 depend on the type of plants used in the (B) experiment. (C) It will show the average growth rate of seedlings that are maintained in a nonsterile environment. (D) It will show the changes that occur in the roots of seedlings following an infection by soil bacteria. Answer A Correct. The seedlings in group 1 will be treated with a solution that contains actively reproducing bacteria, which will be metabolically active. In contrast, the seedlings in group 2 will be treated with a solution that contains heat-killed bacteria, which will be metabolically inactive. The researcher will be able to compare the results for group 1 with those for group 2. The comparison will help the researcher determine whether the changes observed in group 1 depend on the metabolic activity of soil bacteria. Page 6 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ 10. Pectinase is a protein that catalyzes the breakdown of pectic polysaccharides in plant cell walls. A researcher designs an experiment to investigate the effect of salinity on the ability of pectinase to lower the activation energy of the reaction involved. The design of the experiment is presented in Table 1. For each test tube, the researcher will measure the amount of product formed over 20 minutes. Table 1. An experiment to investigate the effect of salinity on pectinase function Test Sodium Chloride Concentration Temperature Substrate Pectinase Tube (molar) (degrees C) Added Added 1 23 Yes No 2 23 Yes Yes 3 23 Yes No 4 23 Yes Yes 5 23 Yes No 6 23 Yes Yes 7 23 Yes No 8 23 Yes Yes Which of the following statements best helps justify the inclusion of test tube 5 in the experiment? (A) It will act as a control for test tube 4 by showing the effect of the presence or absence of the substrate. (B) It will act as a control for test tube 4 by showing the effect of a change in environmental temperature. (C) It will act as a control for test tube 6 by showing the effect of the presence or absence of the enzyme. (D) It will act as a control for test tube 6 by showing the effect of a change in sodium chloride concentration. Answer C Correct. Test tube 5 will act as a control for test tube 6. The solutions in test tubes 5 and 6 are nearly identical except that the researcher will add pectinase to test tube 6 but not to test tube 5. A comparison of the data for test tubes 5 and 6 will show the effect of the presence or absence of the enzyme. AP Biology Page 7 of 18 Scoring Guide Unit 3 Progress Check: MCQ 11. Researchers investigated the effect of urea on the three-dimensional structure of a certain enzyme. The researchers dissolved the enzyme in an aqueous buffer solution and added urea to the solution. The enzyme did not appear to have a secondary or tertiary structure. The researchers carefully removed the urea from the solution and determined that the enzyme had the original secondary and tertiary structure again. Based on the results of the experiment, which of the following statements best predicts the effect of urea on the enzyme’s function? (A) Function will be disrupted by adding the urea and regained by removing the urea. (B) Function will be disrupted by adding the urea, but it will not be regained by removing the urea. (C) Function will be gained by adding the urea and disrupted by removing the urea. (D) Function will be unaffected by the addition and removal of the urea. Answer A Correct. Based on the information, adding the urea denatures the enzyme, which will disrupt the enzyme’s function by disrupting the active site. In contrast, removing the urea causes the enzyme to refold, which will restore the active site and the enzyme’s function. Page 8 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ 12. In an experiment, a researcher prepares a reaction mixture by dissolving a substance in a buffered solution. The substance is the substrate of a certain enzyme. The researcher adds a small amount of the enzyme to the reaction mixture and measures the amount of product that is formed over time. The data are represented in Figure 1. Figure 1. The amount of product formed by an enzyme-catalyzed reaction over time Which of the following best predicts the immediate result of adding more substrate to the reaction mixture at the point indicated by the arrow in Figure 1? (A) The amount of product will decrease until the reaction rate goes to zero. The amount of product will decrease until the reaction reaches its equilibrium point or until the enzyme (B) is been used up by the reaction. The amount of product will increase until the reaction reaches its equilibrium point or until the substrate (C) is used up by the reaction. The amount of product will increase without stopping because the enzyme will be unchanged by the (D) reaction. Answer C Correct. The graph shown in Figure 1 indicates that the amount of product became constant as a consequence of the reaction reaching its equilibrium point or as a consequence of the substrate being used up. Adding more substrate will likely result in an increase in the amount of product because the reaction catalyzed by the enzyme will convert the added substrate into product. AP Biology Page 9 of 18 Scoring Guide Unit 3 Progress Check: MCQ 13. European flycatchers feed caterpillars to their hatchlings. Graph 1 shows the average dates of hatching and fledging (leaving the nest), and the biomass of the caterpillars between early May (when flycatcher young hatch) and June (when fledging of young occurs). Graph 1. Comparison of European flycatcher hatching and fledging dates and caterpillar biomass Based on the data, scientists claim that the reproductive behavior of European flycatchers is influenced by the availability of energy sources. Which of the following statements best justifies this claim? Young European flycatchers hatch from eggs when caterpillar biomass is available for the young birds (A) to consume and convert into energy for growth. European flycatcher hatchlings begin to need energy to leave the nest only after the caterpillars have (B) turned into pupae. Female European flycatchers require energy to lay eggs, so they lay their eggs when the caterpillar (C) biomass is maximal. The energy requirements for hatching European flycatchers and caterpillars are proportional to each (D) other. Page 10 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ 14. A researcher claims that the incorporation of carbon dioxide into organic molecules during photosynthesis does not violate the second law of thermodynamics. Which of the following statements best helps justify the researcher’s claim? (A) Organisms contain enzymes that lower the activation energies of specific chemical reactions. An ecosystem is formed by the interaction of a community of organisms with their surrounding (B) environment. Photosynthetic organisms use the organic molecules produced during photosynthesis for growth and (C) repair. (D) The total system that includes photosynthetic organisms and the Sun becomes less ordered over time. Answer D Correct. Because the total system that includes photosynthetic organisms and the Sun becomes less ordered over time, the incorporation of carbon dioxide molecules into organic molecules that occurs during photosynthesis does not violate the second law of thermodynamics. AP Biology Page 11 of 18 Scoring Guide Unit 3 Progress Check: MCQ 15. Brown fat is a type of fat tissue found in hibernating mammals. Inside the mitochondria of these fat tissue cells, these mammals have an uncoupling protein embedded in the inner mitochondrial membrane. This uncoupling protein allows hydrogen ions to leak from the intermembrane space back into the mitochondrial matrix. Figure 1 shows details of the processes in the inner mitochondrial membrane. Figure 1. Processes in the inner mitochondrial membrane Which of the following statements provides reasoning that supports the claim that brown fatty tissue keeps an animal warm? Page 12 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ The uncoupling protein in this tissue increases the production of and causes more body heat to be (A) produced to warm the animal. The uncoupling protein in this tissue reduces the proton gradient across the membrane and thus produces (B) heat to warm the animal without production. The uncoupling protein in this tissue causes an increase in the proton gradient, which causes more (C) to be produced that helps to warm the animal. The uncoupling protein in this tissue reduces the production of and creates an increase in the (D) proton gradient that allows more heat energy to be produced to warm the animal. Answer B Correct. The uncoupling protein causes a reduction in the proton gradient across the inner mitochondrial membrane because protons constantly leak into the matrix. Heat energy is released as the protons move, but less is made because of the decreased concentration of hydrogen ions available to move across synthase. 16. A researcher claims that spinach leaves capture the most energy from light waves in the range of 500 to 600. To test the claim, the researcher will place spinach leaves in separate chambers and expose the leaves to different wavelengths of light. For each chamber, the researcher will measure the amount of oxygen gas that is produced in one hour. Which of the following graphs best represents data from the experiment that will support the researcher’s claim? AP Biology Page 13 of 18 Scoring Guide Unit 3 Progress Check: MCQ (A) (B) (C) (D) Page 14 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ Answer B Correct. The high levels of produced at wavelengths between 500 and 600 directly support the researcher’s claim. Because oxygen is produced as a by-product of photosynthesis, a greater level of oxygen production indicates a greater level of energy-capture from light. 17. A researcher claims that the initial rise of oxygen in Earth’s early atmosphere, which occurred approximately 2.3 billion years ago, resulted from the metabolic activity of prokaryotic organisms. The claim is based on an interpretation of the geochemical and fossil evidence represented in Figure 1. Figure 1. Selected events in geologic time based on geochemical and fossil evidence Which of the following types of evidence will best support the researcher’s claim? (A) Evidence that some of the earliest eukaryotes used oxygen to produce by cellular respiration (B) Evidence that the earliest plants produced oxygen as a by-product of photosynthesis (C) Evidence that some of the earliest organisms carried out photosynthesis without producing oxygen (D) Evidence that the cyanobacteria produced oxygen as a by-product of photosynthesis Answer D Correct. Based on Figure 1, cyanobacteria appear in the fossil record before the rise of oxygen in Earth’s early atmosphere. The researcher’s claim will be supported by evidence that the cyanobacteria that were on Earth more 2.3 billion years ago produced oxygen as a by-product of photosynthesis. Also, cyanobacteria are prokaryotes, which is consistent with the researcher’s claim. AP Biology Page 15 of 18 Scoring Guide Unit 3 Progress Check: MCQ 18. A researcher claims that a certain herbicide suppresses plant growth by inhibiting chloroplast function. To test the claim, the researcher treats isolated chloroplasts with increasing concentrations of the herbicide. The data from the experiment are presented in Table 1. Table 1. The effect of an herbicide on the function of isolated chloroplasts Herbicide Concentration Difference across Thylakoid μ Membrane Production Very high Moderate Very low Very low Which of the following statements best clarifies how the data support the researcher’s claim? (A) The thylakoid membrane is more permeable to carbon dioxide than to polar molecules. (B) synthase activity depends on a proton gradient across the thylakoid membrane. (C) Some enzymes embedded in the thylakoid membrane catalyze the hydrolysis of. (D) Carbon fixation in the Calvin-Benson cycle takes place in the stroma of chloroplasts. Answer B Correct. The results of the experiment indicate that production in the isolated chloroplasts decreases with increasing concentrations of the herbicide. The data also show that the decrease in production is associated with a decrease in the difference across the thylakoid membrane. The difference is created by a proton gradient, which synthase relies on to produce. 19. A researcher claims that genetic variation provides organisms with the ability to survive and reproduce in different environments. To support the claim, the researcher makes the following observation: bacteria that contain plasmids (small molecules) are resistant to a wider range of antibiotics than are bacteria that contain no plasmids. Which of the following statements best establishes a connection between the observation and the researcher’s claim? (A) Some antibiotics inhibit the synthesis of bacterial cell walls. (B) Some antibiotics inhibit protein synthesis in bacteria cells. (C) Some plasmids cannot exist in a bacterial cell with certain other plasmids. (D) Some plasmids contain antibiotic resistance genes. Page 16 of 18 AP Biology Scoring Guide Unit 3 Progress Check: MCQ Answer D Correct. Because some plasmids contain antibiotic resistance genes, bacteria that contain plasmids are more likely to be resistant to antibiotics than are bacteria that do not contain plasmids. The observation is evidence that genetic variation in the form of plasmids provides bacteria with the ability to survive and reproduce in different environments. 20. Phycobiliproteins are a complex of accessory pigments and proteins found in cyanobacteria but not in green algae. A researcher claims that the phycobiliprotein pigments in cyanobacteria allow the cyanobacteria to survive in certain aquatic niches better than green algae can. Which of the following statements best justifies the researcher’s claim? The additional pigments allow the cyanobacteria to store light energy so that it can be used at night to (A) continue photosynthesis. The additional pigments block light and prevent it from reaching photosynthetic organisms at greater (B) depths, so no photosynthetic organisms can live below the surface waters containing cyanobacteria. The additional pigments require energy and cellular resources to produce, so they can be used as an (C) energy source during times of insufficient light. The additional pigments absorb light at wavelengths that green algae cannot absorb; this may allow (D) cyanobacteria to capture more light energy for photosynthesis than green algae can in certain areas. Answer D Correct. Since the phycobiliprotein pigments absorb light wavelengths not absorbed by green algae, cyanobacteria are able to better perform photosynthesis and survive in areas where there is insufficient light at the needed frequencies for green algae to survive. 21. A researcher claims that budding yeast are able to survive in different environments because they produce enzymes that allow them to use different molecules as sources of matter and energy. Which of the following statements best helps justify the researcher’s claim by providing a relevant example? AP Biology Page 17 of 18 Scoring Guide Unit 3 Progress Check: MCQ Yeast cells produce protein kinases, which are enzymes that catalyze the transfer of phosphate groups (A) from to protein substrates. Yeast cells produce polymerases, which are enzymes that catalyze the conversion of free (B) nucleotides into strands of. Yeast cells produce invertase, which is an enzyme that catalyzes the conversion of the disaccharide (C) sucrose into glucose and fructose. Yeast cells produce catalase, which is an enzyme that catalyzes the conversion of hydrogen peroxide (D) into water and oxygen gas. Answer C Correct. The disaccharide sucrose is not transported efficiently into yeast cells. By producing the enzyme invertase, budding yeast can use the sucrose, glucose, and fructose in the surrounding environment as sources of matter and energy. As such, the production of invertase by budding yeast is a relevant example that will help justify the researcher’s claim. Page 18 of 18 AP Biology AP BIOLOGY Scoring Guide Unit 3 Progress Check: FRQ 1. Read each question carefully. Write your response in the space provided for each part of each question. Answers must be written out in paragraph form. Outlines, bulleted lists, or diagrams alone are not acceptable and will not be scored. Researchers studied the relationship between glucose concentration, oxygen level, and production in one type of mammalian cell. Cells were isolated and cultured in growth medium containing either glucose or glucose and at oxygen levels that varied from to. The researchers determined the concentration of per cell under the different conditions. The concentrations are shown as relative to the maximum concentration obtained when cells were cultured in the presence of glucose and oxygen, standard culture conditions. The data are shown in Table 1. Table 1. Relative concentration of per cell under different growth conditions Concentration of Glucose in Growth Percent of Relative Concentration of per Medium Oxygen Cell (a) Describe the role of oxygen in cellular respiration. m (b)oxygen Using oxygen is the the terminal template, acceptoranofappropriately construct is the terminal electrons tht have passed receptor of labeled through graph that electrons the ETC. to represent havethepassed data in Table 1. through the ETC. glucose concentration appears to have little or no effect on the ATP in the cells. & prediction: the amount of ATP produced will decrease OR no ATP will be produced. justification: the compound is more likely to bind protons where the protons are in↑greater concentration, in the intermembrane space. if the compound then carries the protons across the inner membrane to the matrix, there will no longer be a proton concentration/ pH/ A electrochemical gradient across the inner membrane, and protons will not flow through and power the ATP synthase enzymes. AP Biology Page 1 of 5 Scoring Guide Unit 3 Progress Check: FRQ 2. Read each question carefully. Write your response in the space provided for each part of each question. Answers must be written out in paragraph form. Outlines, bulleted lists, or diagrams alone are not acceptable and will not be scored. Enolase is an enzyme that catalyzes one reaction in glycolysis in all organisms that carry out this process. The amino acid sequence of enolase is similar but not identical in the organisms. Researchers purified enolase from Saccharomyces cerevisiae, a single-celled eukaryotic yeast that grows best at , and from Chloroflexus aurantiacus, a bacterium that grows best at the much higher temperature of. The researchers compared the activity of purified enolase from the two organisms by measuring the rate of the reaction in the presence of varying concentrations of substrate and a constant amount of each enzyme at both and. (a) Depending on the organism, the optimal for enolase to catalyze its reaction is between and. Describe how a below or above this range is likely to affect enolase and its catalytic ability. mummmmmmmmmm (b) aIdentify pH below the efficient the or presenceor above thisnegative appropriate of unable range will to catalyze each organism’s mostthe control the reaction. enolase. likely cause enolase researchers to denature/ most likely used whenchange its shape measuring and be less the reaction rate in (c) The researchers predict that for any particular concentration of substrate, the C. aurantiacus enolase-catalyzed reaction is more rapid at than at. Provide reasoning to justify the researchers’ prediction. the appropriate negative control is to measure the reaction rate (at the varying substrate concentrations) mu Part A without any enzyme present. Select a point value to view scoring criteria, solutions, and/or examples and to score the response. the enolase has a more stable/ functional/ correct/ normal protien structure at the higher temperature & of 55°C than at 37°C because the enzyme is form of an organism that is adapted to growth at 55°C. 0 1 The response indicates that a below or above this range will most likely cause enolase to denature/change its shape and be less efficient or unable to catalyze the reaction. Part B Select a point value to view scoring criteria, solutions, and/or examples and to score the response. 0 1 The response indicates that the appropriate negative control is to measure the reaction rate (at the varying substrate concentrations) without any enzyme present. Part C Select a point value to view scoring criteria, solutions, and/or examples and to score the response. Page 4 of 5 AP Biology Practice Questions Multiple-Choice 1. In prokaryotes, where in the cell do the light-dependent reactions of photosynthesis occur? (A) on the thylakoid membrane (B) on the plasma membrane (C) in the cytoplasm (D) in the nucleoid region Questions 2 and 3 A scientist, who is studying photosynthesis, places a plant in an environment where the oxygen atoms in carbon dioxide are labeled with radioactive 18O but the oxygen atoms in water have nonradioactive 16O. 2. Based on this scenario, predict which product of photosynthesis will contain radioactive 18O. (A) NADPH (B) glucose (C) oxygen gas (D) ATP 3. Based on this scenario, predict which product of photosynthesis will contain nonradioactive 16O. (A) NADPH (B) glucose (C) oxygen gas (D) ATP 4. Which of the following lists the three major parts of the light- independent reactions (the Calvin cycle)? (A) carbon fixation, electron transport chain, reduction (B) carbon fixation, reduction, production of ATP (C) carbon fixation, reduction, regeneration of RuBP (D) reduction, regeneration of RuBP, electron transport chain 5. Which of the following correctly lists the products of the light-dependent reactions? (A) ADP, NADP+, oxygen (B) ATP, NADPH, oxygen (C) G3P, ADP, NADP+ (D) G3P, ATP, NADPH 6. Which of the following correctly lists the products of the Calvin cycle? (A) ADP, NADP+, oxygen (B) ATP, NADPH, oxygen (C) G3P, ADP, NADP+ (D) G3P, ATP, NADPH 7. Which of the following statements correctly identifies the locations of the major parts of photosynthesis in plant cells? (A) Light-dependent reactions occur in the stroma; light-independent reactions occur in the thylakoid. (B) Light-dependent reactions occur in the matrix; light-independent reactions occur in the thylakoid. (C) Light-dependent reactions occur in the thylakoid; light-independent reactions occur in the matrix. (D) Light-dependent reactions occur in the thylakoid; light-independent reactions occur in the stroma. 8. If a thylakoid membrane is punctured so that molecules can freely flow between the thylakoid and the stroma, which of the following processes of photosynthesis will be most directly affected? (A) the formation of G3P (B) the generation of a proton gradient (C) the absorption of light (D) the fixation of carbon 9. Which of the following best describes a relationship between the light- dependent reactions and the Calvin cycle? (A) The light-dependent reactions supply the Calvin cycle with oxygen, and the Calvin cycle returns carbon dioxide to the light-dependent reactions. (B) The light-dependent reactions supply the Calvin cycle with ATP, and the Calvin cycle returns ADP to the light-dependent reactions. (C) The light-dependent reactions supply the Calvin cycle with carbon dioxide, and the Calvin cycle returns oxygen to the light-dependent reactions. (D) The light-dependent reactions supply the Calvin cycle with NADP+, and the Calvin cycle returns NADPH to the light- dependent reactions. 10. In the light-dependent reactions, the final electron acceptor in the electron transport chain is (A) oxygen. (B) water. (C) NAD+. (D) NADP+. mmm Short Free-Response Mem mmme period of time. Use your knowledge about photosynthesis to support the student’s claim. Long Free-Response 13. The following graph shows the absorption spectrum for the pigments chlorophyll a, chlorophyll b, and carotenoids. The following table shows the wavelengths of different colors of visible light. Color Wavelength (nm) Violet 380–450 Blue 450–495 Green 495–570 Yellow 570–590 Orange 590–620 Red 620–750 (a) For each of the three pigments, identify the color of light that will be most absorbed by that pigment. Use the graph to justify your answer. Alt (b) A mutation causes a plant to lose its ability to produce the pigments chlorophyll a and b. A student wants to design an experiment to study the rate of photosynthesis in the plant with this mutation. Identify an appropriate control for the experiment. Identify the independent and dependent variables in the experiment. M(c) The following figure graphs the rate of photosynthesis (as measured by oxygen production) in control plants and in plants with the ummmmmmm mutation described in part (b). mmmum A Calculate the rate of photosynthesis in both sets of plants during the first 30 minutes of the experiment. (d) Plants that use carotenoids as their primary photosynthetic pigment are grown under three different wavelengths of light: 450 nm, 500 nm, and 550 nm. Predict which group of plants will perform the least amount of photosynthesis, and justify your prediction. Practice Questions Multiple-Choice 1. What is the primary purpose of fermentation? (A) to generate ATP (B) to generate pyruvate (C) to generate NAD+ (D) to generate carbon dioxide 2. Which of the following processes does NOT release carbon dioxide? (A) glycolysis (B) oxidation of pyruvate (C) Krebs cycle (D) alcohol fermentation 3. Which of the following statements about glycolysis is NOT correct? (A) Glycolysis occurs in the cytosol. (B) Glycolysis can be carried out by all living organisms. (C) The enzymes of glycolysis are highly conserved. (D) Glycolysis produces a proton gradient. 4. A mutation in mitochondrial DNA causes the creation of a pore in the mitochondrial membrane through which protons can freely pass. Which of the following processes would most likely be disrupted by this mutation? (A) glycolysis (B) Krebs cycle (C) chemiosmosis (D) fermentation 5. During oxidative phosphorylation, ____________ is ____________, and oxygen is ____________. (A) NADH; oxidized; produced (B) NADH; oxidized; reduced (C) NAD+; reduced; oxidized (D) NAD+; reduced; produced 6. Which of the following processes produce ATP? (A) glycolysis, oxidation of pyruvate, Krebs cycle (B) glycolysis, Krebs cycle, chemiosmosis (C) glycolysis, Krebs cycle, fermentation (D) oxidation of pyruvate, Krebs cycle, fermentation 7. What is the role of oxygen in cellular respiration? (A) to combine with carbon and electrons to form carbon dioxide (B) to combine with protons and electrons to form water (C) to remove carbon from glucose to form pyruvate (D) to remove carbon from pyruvate to form alcohol 8. Where are the electron transport chain and ATP synthase located? (A) in the cytosol (B) on the outer membrane of the mitochondria (C) on the inner membrane of the mitochondria (D) in the mitochondrial matrix 9. Which of the following choices correctly describes the flow of electrons in cellular respiration? (A) glucose → Krebs cycle → oxygen → NAD+ (B) glucose → NAD+ → electron transport chain → oxygen (C) glucose → electron transport chain → pyruvate → oxygen - AP Biology Exam Review Multiple Choice Practice 1. The enzyme trypsin aids in protein digestion in the small intestine. The relative activity of trypsin at different pH values is shown in Figure 1. Which of the following statements best explains the activity levels of trypsin shown in Figure 1? a. The small intestine releases inhibitor molecules that block the activity of trypsin unless it is at its optimum pH. b. The number of effective collisions between trypsin and its substrate increase at higher pH values. c. As pH values increase, the substrate concentration decreases, leading to an eventual decline in the rate of the trypsin-catalyzed reaction. d. At extremely low pH values, trypsin is denatured and cannot function efficiently 2. It is estimated that oxygen production first evolved in photosynthetic prokaryotes approximately 2.7 billion years ago. The first photosynthetic prokaryotes are presumed to be similar to today’s cyanobacteria. Which of the following best supports the claim that photosynthetic prokaryotes were responsible for the oxygen in Earth’s atmosphere? a. The light reactions of photosynthesis split carbon dioxide into carbon and oxygen. b. The light reactions of photosynthesis split water into hydrogen ions and oxygen. c. The Calvin cycle splits glucose into carbon, hydrogen, and oxygen. d. The Calvin cycle splits water into hydrogen ions and oxygen. 3. Which of the following questions is most relevant to understanding the Calvin cycle? a. How does chlorophyll capture light? b. How is ATP used in the formation of 3-carbon carbohydrates? c. How is NADP+ reduced to NADPH? d. How is ATP produced in chemiosmosis? Use the following information to answer questions 4 & 5: A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained. Created by: @apbiopenguins Return to Table of Contents 65 AP Biology Exam Review 4. According to the results of this experiment, germination of tobacco seeds during the first week is a. increased by exposure to light b. unaffected by light intensity c. prevented by paper towels d. accelerated in green-leaved seedlings 5. Additional observations were made on day 21, and no yellow-leaved seedlings were found alive in either dish. This is most likely because a. yellow-leaved seedlings were unable to absorb water from the paper towels b. taller green-leaved seedlings blocked the light and prevented photosynthesis c. yellow-leaved seedlings were unable to convert light energy to chemical energy d. a higher rate of respiration in yellow-leaved seedlings depleted their stored nutrients Use the following information to answer questions 6 – 10: Photosynthetic activity can be measured using chloroplasts suspended in a buffered solution containing DCPIP, a dye that can accept electrons from the electron transport chain of photosynthesis. Transfer of electrons to DCPIP decreases the relative absorbance of a specific wavelength of light (605 nm) by a solution that contains the dye. A buffered solution containing chloroplasts and DCPIP was divided equally among six identical samples. The samples were placed at various distances from a lamp, and then all samples were exposed to white light from the lamp for 60 minutes at room temperature. Sample 3 was wrapped in foil to prevent any light from reaching the solution. At 20- minute intervals, the photosynthetic activity in each sample was determined by measuring the relative absorbance of 605 nm light. The results of the experiment are provided below. Relative Absorbance of 605 nm Light (arbitrary units) Sample Distance from 0 min 20 min 40 min 60 min Lamp (cm) 1 15 0.89 0.61 0.34 0.04 2 30 0.90 0.67 0.41 0.14 3* 30 0.88 0.87 0.86 0.87 4 45 0.86 0.69 0.47 0.26 5 60 0.92 0.75 0.59 0.41 6 75 0.88 0.79 0.71 0.58 * Wrapped in foil Created by: @apbiopenguins Return to Table of Contents 66 AP Biology Exam Review 6. Which of the following provides the best indication that light is required for the activation of electron transfer reactions in chloroplasts? a. Calculating the rate of change of the absorbance for sample 1 b. Comparing the observed results for sample 2 and sample 3 c. Repeating the entire experimental procedure at night d. Including multiple trials for all the samples 7. Which of the following can be reasonably concluded from the experimental results? a. Chloroplasts must be suspended in a buffer solution to function properly. b. The optimal temperature for activation of electron transfer is 25°C. c. DCPIP inhibits biochemical reactions in suspended chloroplasts. d. Light from a lamp can substitute for sunlight in stimulating chloroplast processes 8. If an additional sample containing the chloroplast/DCPIP solution was placed at a distance of 90 cm from the lamp, which of the following predictions would be most consistent with the experimental results? a. The concentration of DCPIP in the solution will increase exponentially. b. The absorbance at 60 minutes will be roughly equal to 1.4. c. The change in absorbance over time in the solution will be less than that of the other samples. d. The temperature of the solution will exceed 75°C. 9. Which of the following descriptions of photosynthesis best explains the results of the experiment? a. Availability of electrons for transfer to DCPIP depends on light energy. b. Movement of DCPIP across chloroplast membranes occurs in less than 60 minutes. c. Chlorophyll molecules degrade rapidly in the presence of DCPIP. d. DCPIP can only be used to measure photosynthetic activity at low light levels. 10. Which of the following scientific questions could be investigated using a similar experimental setup? a. How much carbon dioxide is required by a plant cell to produce one molecule of glucose? b. What wavelength of light best activates electron transfer reactions in chloroplasts? c. Which molecule in chloroplasts accepts activated electrons from DCPIP during photosynthesis? d. Are the same genes that are expressed in chloroplasts also expressed in mitochondria? 11. What most likely causes the trends in oxygen concentration shown in the graph below? a. The water becomes colder at night and thus holds more oxygen. b. Respiration in most organisms increases at night. c. More organisms are respiring at night than during the day. d. Photosynthesis produces more oxygen than is consumed by respiration during the day. Created by: @apbiopenguins Return to Table of Contents 67 AP Biology Exam Review 12. 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, 18O, then the oxygen gas released as the reaction proceeds is also labeled with 18O. Which of the following is the most likely explanation? a. During the light reactions of photosynthesis, water is split, the hydrogen atoms combine with the CO2, and oxygen gas is released. b. During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released. c. During the Calvin cycle, water is split, regenerating NADPH from NADP+, and oxygen gas is released. d. During the Calvin cycle, water is split, the hydrogen atoms are added to intermediates of sugar synthesis, and oxygen gas is released. 13. Students in a class measured the mass of various living organisms. They then kept the organisms in the dark for 24 hours before remeasuring them. None of the organisms were provided with nutrients during the 24-hour period. The data are as follows. Organism Starting Mass (g) Final Mass (g) Elodea (submerged 15.10 14.01 aquatic plant) Goldfish 10.10 9.84 Sea anemone 25.60 24.98 Which of the following is the best explanation for the pattern of change in mass of the organisms over time? a. Water loss due to evaporation b. Cellular respiration c. The law of conservation of matter d. Growth and reproduction Use the following information to answer questions 14 & 15: An experiment to measure the rate of respiration in crickets and mice at 10°C and 25°C was performed using a respirometer, an apparatus that measures changes in gas volume. Respiration was measured in mL of O2 consumed per gram of organism over several five-minute trials and the following data were obtained. Organism Temperature (°C) Average respiration (mL O2/g/min) Mouse 10 0.0518 Mouse 25 0.0321 Cricket 10 0.0013 Cricket 25 0.0038 14. 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 b. A plant to produce oxygen c. A glucose reserve d. A valve to release excess water Created by: @apbiopenguins Return to Table of Contents 68 AP Biology Exam Review 15. According to the data, the mice at 10°C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25°C. This is most likely explained by which of the following statements? a. The mice at 10°C had a higher rate of ATP production than the mice at 25°C. b. The mice at 10°C had a lower metabolic rate than the mice at 25°C. c. The mice at 25°C weighed less than the mice at 10°C. d. The mice at 25°C were more active than the mice at 10°C. 16. Where on an enzyme does the substrate bind? a. active site c. C-terminus b. allosteric site d. N-terminus 17. Describe the effect on the free energy of doubling the amount of enzyme. a. double the free energy c. triple the free energy b. half the free energy d. no effect on free energy 18. Which structure is unaffected by denaturation? a. Primary c. Tertiary b. Secondary d. Quaternary 19. Which environmental conditions can cause denaturation of the enzyme? a. slight increase in temperature b. extreme increase in temperature c. decrease in temperature d. extreme increase in temperature and pH changes 20. Which of the following will increase the rate of the reaction? a. increase product c. increase inhibitor b. increase substrate d. increase enzyme 21. Describe why an increase in temperature increases the rate of the reaction. a. increase in temperature increases the speed/kinetic energy of particles b. increase in temperature activates more enzyme to increase the rate c. increase in temperature results in increase in substrate available d. increase in temperature allows for a tighter fit in the active site 22. Describe the difference between competitive and noncompetitive inhibitors. a. noncompetitive binds to active site and competitive binds to other site b. competitive binds to active site and noncompetitive binds to other site c. competitive is irreversible and noncompetitive is reversible binding d. noncompetitive is irreversible and competitive is reversible binding 23. In order to maintain order and power cellular processes, a. energy input must exceed energy loss c. energy loss must exceed energy input b. energy input equals energy loss d. energy loss equals energy input 24. What is the process of an endergonic reaction being fueled by an exergonic reaction called? a. second law of thermodynamics c. first law of thermodynamics b. energy coupling d. endergonic/exergonic switch Created by: @apbiopenguins Return to Table of Contents 69 AP Biology Exam Review 25. Where did photosynthesis first evolve? a. prokaryotic organisms c. eukaryotic organisms b. alien organisms d. abiotic processes 26. What are the products of the light-dependent reactions of photosynthesis? a. ATP & NADH c. NADPH & ATP b. CO2 & H2O d. Organic Compounds & O2 27. What is the function of the electron transport chain between Photosystem II and Photosystem I? a. establish electrochemical gradient of protons b. to funnel electrons into photosystem I for the Calvin cycle c. transport electrons to oxygen to make water d. to synthesize ATP using ATP synthase 28. Where does the Calvin cycle take place? a. thylakoid membrane c. stroma b. cristae d. matrix 29. Where does the electron transport chain take place? a. chloroplasts c. mitochondria b. prokaryotic plasma membrane d. all of the choices 30. Which of the following are electron carriers for the electron transport chain in cellular respiration? a. NADPH c. NADH b. FADH2 d. NADH & FADH2 31. Which process releases energy in glucose to form ATP, NADH, and pyruvate? a. Glycolysis c. Krebs Cycle b. Oxidative Phosphorylation d. Fermentation 32. What is oxidation? a. loss of electrons c. gain of electrons b. loss of water d. gain of water 33. In the electron transport chain of cellular respiration, where is the electrochemical gradient of protons generated? a. cytosol c. matrix b. cristae d. intermembrane space 34. Which process does NOT require oxygen? a. Glycolysis c. Krebs Cycle b. Oxidative Phosphorylation d. Aerobic respiration 35. Describe the pathway of electrons in the light reactions. a. H2O → PSI → ETC → PSII → NADPH b. H2O → PSII → ETC → PSI → NADPH c. H2O → PSII → ETC → PSI → NADH d. H2O → PSI → ETC → PSII → NADH Created by: @apbiopenguins Return to Table of Contents 70