AP Bio Unit 3 Review
The figures below illustrate the similarities between ATP synthesis in mitochondria and chloroplasts. The figures can best assist in answering which of the following questions?
Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?
Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation?
Glycolysis
This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. (A) Glysolysis(B) Krebs cycle (citric acid cycle)(C) Calvin cycle (light-independent reactions of photosynthesis)(D) Light-dependent reactions of photosynthesis(E) Chemiosmosis Process in which O2 is released as a by-product of oxidation-reduction reactions
D
The enzyme hexokinase catalyzes the conversion of glucose to glucose-6-phosphate, which is an important step in glycolysis. The reaction involves the transfer of a phosphate group from ATP to glucose. Either a glucose molecule or a water molecule can fit in the active site of hexokinase. The presence of a water molecule in hexokinase's active site would result in the hydrolysis of ATP to ADP instead of the conversion of glucose to glucose-6-phosphate. Which of the following statements best helps explain the reaction specificity of hexokinase?
Glucose has the right shape and charge to cause hexokinase to undergo a structural change needed for catalysis, whereas water does not.
What most likely causes the trends in oxygen concentration shown in the graph above?
Photosynthesis produces more oxygen than is consumed by respiration during the day.
This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. (A) Glysolysis(B) Krebs cycle (citric acid cycle)(C) Calvin cycle (light-independent reactions of photosynthesis)(D) Light-dependent reactions of photosynthesis(E) Chemiosmosis Process found in both photosynthesis and cellular respiration
E
Which of the following questions will best direct an investigation of the mechanism of ATP synthase?
Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient?
A researcher is investigating the effects of a chemical that makes thylakoid 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.
Gelatin is a protein that is derived from collagen which is found in the bones, skin, and connective tissue of animals. To investigate the ability of various enzymes to digest gelatin, a group of students set up an assay involving camera film. Camera film contains gelatin and appears black when exposed to light but turns clear as the gelatin gets broken down. The students incubated pieces of exposed camera film in test tubes, each containing one of three different enzyme solutions (trypsin, lipase, or amylase) as indicated in Figure 1. The students recorded the time it took for the enzymes to digest the gelatin in each test tube, turning the film from black to clear. Figure 1. Diagram of experimental setup. Which of the following would be the most appropriate control for this experiment?
A test tube containing a piece of exposed camera film submerged in water
A respirometer is a container used to measure the amount of oxygen consumed by an organism. A respirometer was used to determine how environmental temperature affects the uptake of oxygen in one 300-gram rat and one 50-gram mouse. The results of this experiment are shown on the graph below. Which of the following hypotheses is best supported by the results of this experiment?
Metabolic rate per gram of tissue is higher in smaller mammals.
A researcher claims that different enzymes exhibit maximal function over different pH ranges. To test the claim, the researcher carries out an experiment that includes three different enzymes: pepsin, salivary amylase, and arginase. The results of the experiment are represented in Figure 1. Figure 1. The effect of pH on three different enzymes Which of the following actions will provide the most appropriate negative control for the experiment?
Repeating the experiment with denatured enzymes
A researcher proposes a model of an enzyme-catalyzed reaction in which a reactant is converted to a product. The model is based on the idea that the reactant passes through a transition state within the enzyme-substrate complex before the reactant is converted to the product. Which of the following statements best helps explain how the enzyme speeds up the reaction?
The enzyme's active site binds to and stabilizes the transition state, which decreases the activation energy of the reaction.
A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes. Which of the following must remain the same for all trials of this experiment?
The initial concentration of the substrate
Which of the following is an important difference between light-dependent and light-independent reactions of photosynthesis?
The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH.
Which of the following statements best helps explain the reaction specificity of an enzyme?
The shape and charge of the substrates are compatible with the active site of the enzyme.
Which of the following best describes the function of the coenzymes NAD+ and FAD in eukaryotic cellular respiration?
They accept electrons during oxidation-reduction reactions.
A researcher claims that some bacteria contain factors that influence the function of a particular enzyme but other bacteria do not. To test the claim experimentally, the researcher will grow two different bacterial strains in separate liquid cultures and isolate the contents of the cells in each culture. The researcher will add different combinations of cellular contents, substrate, and enzyme to test tubes containing a buffer solution adjusted to the optimal pH of the enzyme and then measure the rate of product formation. The design of the researcher's experiment is presented in Table 1. Table 1. An experiment for investigating the influence of bacterial factors on enzyme function Test Tube Source of Cellular Contents Cellular Contents Added Substrate Added Enzyme Added 1 Strain 1 No Yes Yes 2Strain 1YesNoYes3 Strain 1 Yes Yes No 4 Strain 1 Yes Yes Yes 5 Strain 2 No Yes Yes 6 Strain 2 YesNo Yes 7 Strain 2 Yes Yes No 8Strain 2YesYesYes Which of the following statements best justifies the inclusion of test tubes 3 and 7 in the experiment?
They will show whether the isolated cellular contents have enzymatic activity.
ATP serves as a common energy source for organisms because
its energy can be easily transferred to do cellular work
The enzyme peroxidase is found in many organisms. It catalyzes the breakdown of hydrogen peroxide into water and oxygen gas. The rate of peroxidase activity at different pH values was assessed by students in the lab. The students' results are shown in graph 1. Graph 1. Effect of pH on peroxidase activity If the experiment is repeated at pH 11, the observed activity level of the enzyme will most likely be
lower than the level at pH 9
Carbohydrate-synthesizing reactions of photosynthesis directly require
products of the light reactions
During respiration, most ATP is formed as a direct result of the net movement of
protons down a concentration gradient
This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. (A) Glysolysis(B) Krebs cycle (citric acid cycle)(C) Calvin cycle (light-independent reactions of photosynthesis)(D) Light-dependent reactions of photosynthesis(E) Chemiosmosis Process in which CO2, is released as a by-product of oxidation-reduction reactions
B
Protein digestion in humans is primarily carried out by three enzymes. Pepsin is found in the stomach (pH2), where it aids in the breakdown of large proteins into smaller peptides, while trypsin and chymotrypsin are found in the small intestine (pH8), where they aid in the further breakdown of the proteins into amino acids and dipeptides that can be absorbed into the bloodstream. Graph 1 shows the effect of pH on the activity levels of the three enzymes. Graph 1. Relative activity of pepsin, trypsin, and chymotrypsin at pH 0 through 11 Which of the following best predicts how the structure and function of pepsin will change as it enters the small intestine?
Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease.
This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. (A) Glysolysis(B) Krebs cycle (citric acid cycle)(C) Calvin cycle (light-independent reactions of photosynthesis)(D) Light-dependent reactions of photosynthesis(E) Chemiosmosis Process in which sugar is oxidized to pyruvic acid
A
Scientists investigated the effect of oxygen levels on the net rate of carbon fixation in two types of plants. The plants were grown in either well-watered soil (control) or dry soil and then exposed to either 21% or 1% O2. The net rate of CO2 fixation for both types of plants was measured. Data are shown in Figure 1 and Figure 2. Figure 1. Net rate of CO2 fixation in two types of plants grown in wet (control) or dry soil at 21% O2Figure 2. Net rate of CO2 fixation in two types of plants grown in wet (control) or dry soil at 1% O2 Which of the following statements about the rate of CO2 fixation in the two types of plants is supported by the data shown in the figures?
At 21% O2, plant type 2 has a lower rate of CO2 fixation than plant type 1 does in both types of soil.
A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants. Which of the following statements best supports the researcher's claim?
Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.
Alcohol dehydrogenase (ADH) is an enzyme that aids in the decomposition of ethyl alcohol (C2H5OH) into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on ADH. When attached to ADH, methyl alcohol is converted to formaldehyde, which is toxic in the body. Which of the following statements best predicts the effect of increasing the concentration of substrate (ethyl alcohol), while keeping the concentration of the inhibitor (methyl alcohol) constant?
Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will increase.
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?
During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released.
A researcher claims that increasing the environmental temperature by 10°C will double the rate of an enzyme-catalyzed reaction. To test the claim, the researcher designs an experiment that uses a particular enzyme isolated from plants. The design of the experiment is presented in Table 1. For each test tube in the experiment, the researcher will measure the rate of product formation. Test Tube Temperature (°C) Substrate Added Enzyme Added Pretreated by Boiling 1 15 Yes Yes No 2 25 No Yes No 3 25 Yes No No 4 25 Yes Yes No 5 25 Yes Yes Yes 6 35 Yes Yes No Which of the following statements best helps justify the inclusion of test tube 5 as a control in the experiment?
It will provide a measurement of product formation in the presence of a denatured enzyme.
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?
The light reactions of photosynthesis split water into hydrogen ions and oxygen.
Pyruvate dehydrogenase is an enzyme that converts pyruvate to acetyl-CoA. Acetyl-CoA is further metabolized in the Krebs cycle. A researcher measured the accumulation of acetyl-CoA in a reaction containing pyruvate and pyruvate dehydrogenase under several different conditions (Figure 1). Figure 1. Accumulation of acetyl-CoA under different conditions Which of the following best describes the cellular location where pyruvate dehydrogenase is most likely active?
The mitochondrial matrix
The carbon 'that makes up organic molecules in plants is derived directly from
carbon fixed in photosynthesis
Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?
A buildup of lactic acid in the muscle tissue due to fermentation
The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions?
ATP and NADPH
Amylase is a protein that catalyzes the conversion of starch to simple sugars. Amylase activity in an aqueous solution can be measured by using iodine as a starch indicator. A solution containing iodine and starch will have a dark-blue color, whereas a solution containing iodine but no starch will have a light-brown color. The color change of an iodine solution from dark blue to light brown can be used to measure the rate at which starch is converted to simple sugars. A student designs an experiment to investigate the effect of environmental pH on amylase function. The design of the experiment is presented in Table 1. Table 1. An experiment for investigating the effect of pH on amylase function Test Tube Environmental pHStarch Added Amylase Added Iodine Added Pretreated by Boiling I5 Yes Yes Yes No II6 Yes Yes Yes No III7 No Yes Yes No IV7 Yes No Yes No V7 Yes Yes Yes Yes VI7 Yes Yes Yes No VII8 Yes Yes Yes No VIII9 Yes Yes Yes No Which of the following statements best justifies the inclusion of test tube V as a control in the experiment?
It will show the color change that occurs in the absence of enzyme activity.
Dichlorophenolindophenol (DCPIP) is a chemical dye. When DCPIP is chemically reduced, it changes color from blue to clear. DCPIP can be used as an electron acceptor in experiments that measure the rate of electron transport through the electron transport chain. A student performed an experiment to study the effects of a chemical, DCMU, on photosynthesis. The student prepared four tubes with a liquid buffer and chloroplasts that had been extracted from spinach leaves. The student then added DCPIP to three of the tubes and added DCMU to one of them. Additionally, tube 3 was wrapped in tin foil. The contents of each tube are shown in the table. The student then incubated each tube for 60 minutes and measured the absorbance (A600) of each solution at five-minute intervals. The absorbance readings of each solution are shown in Figure 1. Which of the following claims is best supported by the experimental results?
Light is required for the electron transport chain to transfer electrons.
For following group of questions first study the description of the situation and diagrams and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. A student studied the effects of light intensity on oxygen production in green algae. The algae were suspended in water inside a sealed glass jar, and the jar was placed into a constant-temperature, lightproof box containing a light source. A probe was inserted into the jar to record the concentration of oxygen. The probe was connected to a recording device. The setup is shown below. The student decreased the intensity of the light hourly and recorded the corresponding changes in oxygen concentration. The graph below shows the results from the recording device. Based on the data shown, changes in the light intensity resulted in changes in the rate of which of the following processes?
Photosynthesis
The figure above shows an organelle typically found in eukaryotic cells. Which of the following best describes the function of the double membrane system of this organelle?
The inner membrane has specialized proteins that create a hydrogen ion concentration gradient between the intermembrane space and the matrix.