BIOL 1406 - Test 4
44) Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization? A) ATP is more abundant near the plasma membrane. B) They can more readily encounter and phosphorylate other membrane proteins. C) Membrane localization lowers the activation energy of the phosphorylation reaction. D) They flip back and forth across the membrane to access target proteins on either side. E) They require phospholipids as a cofactor.
Answer: B Topic: Concept 8.4 Skill: Application/Analysis
32) Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's A) entropy. B) activation energy. C) endothermic level. D) equilibrium point. E) free-energy content.
Answer: B Topic: Concept 8.4 Skill: Knowledge/Comprehension
72) Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to A) inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle. B) activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle. C) inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle. D) activate the enzyme and increase the rates of glycolysis and the citric acid cycle. E) inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate.
Answer: A Topic: Concept 9.6 Skill: Knowledge/Comprehension
34) Which of the following statements regarding enzymes is true? A) Enzymes increase the rate of a reaction by making the reaction more exergonic. B) Enzymes increase the rate of a reaction by lowering the activation energy barrier. C) Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. D) Enzymes change the equilibrium point of the reactions they catalyze. E) Enzymes make the rate of a reaction independent of substrate concentrations.
Answer: B Topic: Concept 8.4 Skill: Knowledge/Comprehension
36) The active site of an enzyme is the region that A) binds allosteric regulators of the enzyme. B) is involved in the catalytic reaction of the enzyme. C) binds noncompetitive inhibitors of the enzyme. D) is inhibited by the presence of a coenzyme or a cofactor.
Answer: B Topic: Concept 8.4 Skill: Knowledge/Comprehension
46) How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? A) by binding at the active site of the enzyme B) by changing the shape of the enzyme's active site C) by changing the free energy change of the reaction D) by acting as a coenzyme for the reaction E) by decreasing the activation energy of the reaction
Answer: B Topic: Concept 8.4 Skill: Knowledge/Comprehension
35) The primary role of oxygen in cellular respiration is to A) yield energy in the form of ATP as it is passed down the respiratory chain. B) act as an acceptor for electrons and hydrogen, forming water. C) combine with carbon, forming CO2. D) combine with lactate, forming pyruvate. E) catalyze the reactions of glycolysis.
Answer: B Topic: Concept 9.4 Skill: Knowledge/Comprehension
50) What is proton-motive force? A) the force required to remove an electron from hydrogen B) the force exerted on a proton by a transmembrane proton concentration gradient C) the force that moves hydrogen into the intermembrane space D) the force that moves hydrogen into the mitochondrion E) the force that moves hydrogen to NAD+
Answer: B Topic: Concept 9.4 Skill: Knowledge/Comprehension
59) The ATP made during fermentation is generated by which of the following? A) the electron transport chain B) substrate-level phosphorylation C) chemiosmosis D) oxidative phosphorylation E) aerobic respiration
Answer: B Topic: Concept 9.5 Skill: Knowledge/Comprehension
68) When skeletal muscle cells undergo anaerobic respiration, they become fatigued and painful. This is now known to be caused by A) buildup of pyruvate. B) buildup of lactate. C) increase in sodium ions. D) increase in potassium ions. E) increase in ethanol.
Answer: B Topic: Concept 9.5 Skill: Knowledge/Comprehension
65) Why is glycolysis considered to be one of the first metabolic pathways to have evolved? A) It produces much less ATP than does oxidative phosphorylation. B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. C) It is found in prokaryotic cells but not in eukaryotic cells. D) It relies on chemiosmosis, which is a metabolic mechanism present only in the first cells' prokaryotic cells. E) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.
Answer: B Topic: Concept 9.5 Skill: Synthesis/Evaluation
67) When skeletal muscle cells are oxygen-deprived, the heart still pumps. What must the heart muscle cells be able to do? A) derive sufficient energy from fermentation B) continue aerobic metabolism when skeletal muscle cannot C) transform lactate to pyruvate again D) remove lactate from the blood E) remove oxygen from lactate
Answer: B Topic: Concept 9.5 Skill: Synthesis/Evaluation
79) During intense exercise, as skeletal muscle cells go into anaerobiosis, the human body will increase its catabolism of A) fats only. B) carbohydrates only. C) proteins only. D) fats, carbohydrates, and proteins. E) fats and proteins only.
Answer: B Topic: Concept 9.6 Skill: Application/Analysis
78) High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of A) competitive inhibition. B) allosteric regulation. C) the specificity of enzymes for their substrates. D) an enzyme requiring a cofactor. E) positive feedback regulation.
Answer: B Topic: Concepts 8.5, 9.6 Skill: Application/Analysis
6) In autotrophic bacteria, where are the enzymes located that can carry on carbon fixation (reduction of carbon dioxide to carbohydrate)? A) in chloroplast membranes B) in chloroplast stroma C) in the cytosol D) in the nucleoid E) in the infolded plasma membrane
Answer: C Topic: Concept 10.1 Skill: Application/Analysis
16) As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. Where did the extra ATP molecules come from? A) photosystem II B) photosystem I C) cyclic electron flow D) linear electron flow E) chlorophyll
Answer: C Topic: Concept 10.2 Skill: Application/Analysis
38) The accumulation of free oxygen in Earth's atmosphere began A) with the origin of life and respiratory metabolism. B) with the origin of photosynthetic bacteria that had photosystem I. C) with the origin of cyanobacteria that had both photosystem I and photosystem II. D) with the origin of chloroplasts in photosynthetic eukaryotic algae. E) with the origin of land plants.
Answer: C Topic: Concept 10.2 Skill: Application/Analysis
15) What are the products of linear photophosphorylation? A) heat and fluorescence B) ATP and P700 C) ATP and NADPH D) ADP and NADP E) P700 and P680
Answer: C Topic: Concept 10.2 Skill: Knowledge/Comprehension
21) In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from A) the stroma to the photosystem II. B) the matrix to the stroma. C) the stroma to the thylakoid space. D) the intermembrane space to the matrix. E) the thylakoid space to the stroma.
Answer: C Topic: Concept 10.2 Skill: Knowledge/Comprehension
24) In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during A) photosynthesis only. B) respiration only. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration only.
Answer: C Topic: Concept 10.2 Skill: Knowledge/Comprehension
29) A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition? A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. B) His cells cannot move NADH from glycolysis into the mitochondria. C) His cells contain something that inhibits oxygen use in his mitochondria. D) His cells lack the enzyme in glycolysis that forms pyruvate. E) His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
Answer: A Topic: Concepts 9.3, 9.6 Skill: Synthesis/Evaluation
7) When oxygen is released as a result of photosynthesis, it is a direct by-product of A) reducing NADP+. B) splitting water molecules. C) chemiosmosis. D) the electron transfer system of photosystem I. E) the electron transfer system of photosystem II.
Answer: B Topic: Concept 10.1 Skill: Knowledge/Comprehension
18) What does the chemiosmotic process in chloroplasts involve? A) establishment of a proton gradient across the thylakoid membrane B) diffusion of electrons through the thylakoid membrane C) reduction of water to produce ATP energy D) movement of water by osmosis into the thylakoid space from the stroma E) formation of glucose, using carbon dioxide, NADPH, and ATP
Answer: A Topic: Concept 10.2 Skill: Knowledge/Comprehension
19) Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen? A) The isolated chloroplasts will make ATP. B) The Calvin cycle will be activated. C) Cyclic photophosphorylation will occur. D) The isolated chloroplasts will generate oxygen gas. E) The isolated chloroplasts will reduce NADP+ to NADPH.
Answer: A Topic: Concept 10.2 Skill: Knowledge/Comprehension
23) Where are the molecules of the electron transport chain found in plant cells? A) thylakoid membranes of chloroplasts B) stroma of chloroplasts C) outer membrane of mitochondria D) matrix of mitochondria E) cytoplasm
Answer: A Topic: Concept 10.2 Skill: Knowledge/Comprehension
26) Reduction of NADP+ occurs during A) photosynthesis. B) respiration. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration.
Answer: A Topic: Concept 10.2 Skill: Knowledge/Comprehension
36) In a cyanobacterium, the reactions that produce NADPH occur in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.
Answer: A Topic: Concept 10.2 Skill: Knowledge/Comprehension
37) The reactions that produce molecular oxygen (O2) take place in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but are not part of photosynthesis.
Answer: A Topic: Concept 10.2 Skill: Knowledge/Comprehension
28) Generation of proton gradients across membranes occurs during A) photosynthesis. B) respiration. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration.
Answer: C Topic: Concept 10.2 Skill: Knowledge/Comprehension
60) Plants photosynthesize only in the light. Plants respire A) in the dark only. B) in the light only. C) both in light and dark. D) never-they get their ATP from photophosphorylation. E) only when excessive light energy induces photorespiration.
Answer: C Topic: Concept 10.4 Skill: Application/Analysis
56) The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why? A) Each one minimizes both water loss and rate of photosynthesis. B) C4 compromises on water loss and CAM compromises on photorespiration. C) Both minimize photorespiration but expend more ATP during carbon fixation. D) CAM plants allow more water loss, while C4 plants allow less CO2 into the plant. E) C4 plants allow less water loss but CAM plants allow more water loss.
Answer: C Topic: Concept 10.4 Skill: Knowledge/Comprehension
2) Which of the following is (are) true for anabolic pathways? A) They do not depend on enzymes. B) They are usually highly spontaneous chemical reactions. C) They consume energy to build up polymers from monomers. D) They release energy as they degrade polymers to monomers. E) They consume energy to decrease the entropy of the organism and its environment.
Answer: C Topic: Concept 8.1 Skill: Knowledge/Comprehension
18) Which of the following shows the correct changes in thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein? A) +ΔH, +ΔS, +ΔG B) +ΔH, -ΔS, -ΔG C) +ΔH, -ΔS, +ΔG D) -ΔH, -ΔS, +ΔG E) -ΔH, +ΔS, +ΔG
Answer: C Topic: Concept 8.2 Skill: Application/Analysis
14) The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct? A) ΔS is the change in enthalpy, a measure of randomness. B) ΔH is the change in entropy, the energy available to do work. C) ΔG is the change in free energy. D) T is the temperature in degrees Celsius.
Answer: C Topic: Concept 8.2 Skill: Knowledge/Comprehension
14) Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be A) to determine if they have thylakoids in the chloroplasts. B) to test for liberation of O2 in the light. C) to test for CO2 fixation in the dark. D) to do experiments to generate an action spectrum. E) to test for production of either sucrose or starch.
Answer: B Topic: Concept 10.2 Skill: Application/Analysis
8) A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment? A) red and yellow B) blue and violet C) green and yellow D) blue, green, and red E) green, blue, and yellow
Answer: B Topic: Concept 10.2 Skill: Application/Analysis
25) Which of the following is most similar in structure to ATP? A) a pentose sugar B) a DNA nucleotide C) an RNA nucleotide D) an amino acid with three phosphate groups attached E) a phospholipid
Answer: C Topic: Concept 8.3 Skill: Knowledge/Comprehension
10) In the thylakoid membranes, what is the main role of the antenna pigment molecules? A) split water and release oxygen to the reaction-center chlorophyll B) harvest photons and transfer light energy to the reaction-center chlorophyll C) synthesize ATP from ADP and i D) transfer electrons to ferredoxin and then NADPH E) concentrate photons within the stroma
Answer: B Topic: Concept 10.2 Skill: Knowledge/Comprehension
13) Which of the following are directly associated with photosystem I? A) harvesting of light energy by ATP B) receiving electrons from the thylakoid membrane electron transport chain C) generation of molecular oxygen D) extraction of hydrogen electrons from the splitting of water E) passing electrons to the thylakoid membrane electron transport chain
Answer: B Topic: Concept 10.2 Skill: Knowledge/Comprehension
22) Which of the following statements best describes the relationship between photosynthesis and respiration? A) Respiration runs the biochemical pathways of photosynthesis in reverse. B) Photosynthesis stores energy in complex organic molecules, whereas respiration releases it. C) Photosynthesis occurs only in plants and respiration occurs only in animals. D) ATP molecules are produced in photosynthesis and used up in respiration. E) Respiration is anabolic and photosynthesis is catabolic.
Answer: B Topic: Concept 10.2 Skill: Knowledge/Comprehension
25) Reduction of oxygen to form water occurs during A) photosynthesis only. B) respiration only. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration only.
Answer: B Topic: Concept 10.2 Skill: Knowledge/Comprehension
29) What is the relationship between wavelength of light and the quantity of energy per photon? A) They have a direct, linear relationship. B) They are inversely related. C) They are logarithmically related. D) They are separate phenomena. E) They are only related in certain parts of the spectrum.
Answer: B Topic: Concept 10.2 Skill: Knowledge/Comprehension
33) Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants? A) They serve as accessory pigments to increase light absorption. B) They protect against oxidative damage from excessive light energy. C) They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation. D) They reflect orange light and enhance red light absorption by chlorophyll. E) They take up and remove toxins from the groundwater.
Answer: B Topic: Concept 10.2 Skill: Knowledge/Comprehension
31) Some photosynthetic bacteria (e.g., purple sulfur bacteria) have only photosystem I, whereas others (e.g., cyanobacteria) have both photosystem I and photosystem II. Which of the following might this observation imply? A) Photosystem II was selected against in some species. B) Photosynthesis with only photosystem I is more ancestral. C) Photosystem II may have evolved to be more photoprotective. D) Linear electron flow is more primitive than cyclic flow of electrons. E) Cyclic flow is more necessary than linear electron flow.
Answer: B Topic: Concept 10.2 Skill: Synthesis/Evaluation
42) In C3 photosynthesis, the reactions that require ATP take place in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.
Answer: B Topic: Concept 10.3 Skill: Knowledge/Comprehension
45) Reactions that require CO2 take place in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.
Answer: B Topic: Concept 10.3 Skill: Knowledge/Comprehension
59) If atmospheric CO2 concentrations increase twofold or more, how will plants be affected, disregarding any changes in climate? A) All plants will experience increased rates of photosynthesis. B) C3 plants will have faster growth; C4 plants will be minimally affected. C) C4 plants will have faster growth; C3 plants will be minimally affected. D) C3 plants will have faster growth; C4 plants will have slower growth. E) Plant growth will not be affected because atmospheric CO2 concentrations are never limiting for plant growth.
Answer: B Topic: Concept 10.4 Skill: Application/Analysis
51) Photorespiration occurs when rubisco reacts RuBP with A) CO2. B) O2. C) glyceraldehyde 3-phosphate. D) 3-phosphoglycerate. E) NADPH.
Answer: B Topic: Concept 10.4 Skill: Knowledge/Comprehension
51) Protein kinases are enzymes that catalyze phosphorylation of target proteins at specific sites, whereas protein phosphatases catalyze removal of phosphate(s) from phosphorylated proteins. Phosphorylation and dephosphorylation can function as an on-off switch for a protein's activity, most likely through A) the change in a protein's charge leading to a conformational change. B) the change in a protein's charge leading to cleavage. C) a change in the optimal pH at which a reaction will occur. D) a change in the optimal temperature at which a reaction will occur. E) the excision of one or more peptides.
Answer: A Topic: Concept 8.5 Skill: Synthesis/Evaluation
10) The ATP made during glycolysis is generated by A) substrate-level phosphorylation. B) electron transport. C) photophosphorylation. D) chemiosmosis. E) oxidation of NADH to NAD+.
Answer: A Topic: Concept 9.1 Skill: Knowledge/Comprehension
3) When electrons move closer to a more electronegative atom, what happens? A) The more electronegative atom is reduced, and energy is released. B) The more electronegative atom is reduced, and energy is consumed. C) The more electronegative atom is oxidized, and energy is consumed. D) The more electronegative atom is oxidized, and energy is released. E) The more electronegative atom is reduced, and entropy decreases.
Answer: A Topic: Concept 9.1 Skill: Knowledge/Comprehension
5) Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) C6H12O6 is reduced and CO2 is oxidized. E) O2 is reduced and CO2 is oxidized.
Answer: A Topic: Concept 9.1 Skill: Knowledge/Comprehension
8) Which of the following statements describes NAD+? A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. B) NAD+ has more chemical energy than NADH. C) NAD+ is oxidized by the action of hydrogenases. D) NAD+ can donate electrons for use in oxidative phosphorylation. E) In the absence of NAD+, glycolysis can still function.
Answer: A Topic: Concept 9.1 Skill: Knowledge/Comprehension
24) The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane. How does pyruvate enter the mitochondrion? A) active transport B) diffusion C) facilitated diffusion D) through a channel E) through a pore
Answer: A Topic: Concept 9.3 Skill: Application/Analysis
27) How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? A) two B) four C) six D) eight E) ten
Answer: A Topic: Concept 9.3 Skill: Knowledge/Comprehension
56) Which of the following normally occurs regardless of whether or not oxygen (O2) is present? A) glycolysis B) fermentation C) oxidation of pyruvate to acetyl CoA D) citric acid cycle E) oxidative phosphorylation (chemiosmosis)
Answer: A Topic: Concept 9.5 Skill: Knowledge/Comprehension
57) Which of the following occurs in the cytosol of a eukaryotic cell? A) glycolysis and fermentation B) fermentation and chemiosmosis C) oxidation of pyruvate to acetyl CoA D) citric acid cycle E) oxidative phosphorylation
Answer: A Topic: Concept 9.5 Skill: Knowledge/Comprehension
60) In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of A) ATP, CO2, and ethanol (ethyl alcohol). B) ATP, CO2, and lactate. C) ATP, NADH, and pyruvate. D) ATP, pyruvate, and oxygen. E) ATP, pyruvate, and acetyl CoA.
Answer: A Topic: Concept 9.5 Skill: Knowledge/Comprehension
61) In alcohol fermentation, NAD+ is regenerated from NADH by A) reduction of acetaldehyde to ethanol (ethyl alcohol). B) oxidation of pyruvate to acetyl CoA. C) reduction of pyruvate to form lactate. D) oxidation of ethanol to acetyl CoA. E) reduction of ethanol to pyruvate.
Answer: A Topic: Concept 9.5 Skill: Knowledge/Comprehension
53) Why are C4 plants able to photosynthesize with no apparent photorespiration? A) They do not participate in the Calvin cycle. B) They use PEP carboxylase to initially fix CO2. C) They are adapted to cold, wet climates. D) They conserve water more efficiently. E) They exclude oxygen from their tissues.
Answer: B Topic: Concept 10.4 Skill: Knowledge/Comprehension
55) Photorespiration lowers the efficiency of photosynthesis by A) carbon dioxide molecules. B) 3-phosphoglycerate molecules. C) ATP molecules. D) ribulose bisphosphate molecules. E) RuBP carboxylase molecules.
Answer: B Topic: Concept 10.4 Skill: Knowledge/Comprehension
4) For living organisms, which of the following is an important consequence of the first law of thermodynamics? A) The energy content of an organism is constant. B) The organism ultimately must obtain all of the necessary energy for life from its environment. C) The entropy of an organism decreases with time as the organism grows in complexity. D) Organisms grow by converting energy into organic matter. E) Life does not obey the first law of thermodynamics.
Answer: B Topic: Concept 8.1 Skill: Synthesis/Evaluation
19) When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows: A) +ΔG, +ΔH, +ΔS. B) +ΔG, +ΔH, -ΔS. C) +ΔG, -ΔH, -ΔS. D) -ΔG, +ΔH, +ΔS. E) -ΔG, -ΔH, -ΔS.
Answer: B Topic: Concept 8.2 Skill: Application/Analysis
16) Which of the following is true for all exergonic reactions? A) The products have more total energy than the reactants. B) The reaction proceeds with a net release of free energy. C) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. D) A net input of energy from the surroundings is required for the reactions to proceed. E) The reactions are rapid.
Answer: B Topic: Concept 8.2 Skill: Knowledge/Comprehension
21) Which of the following best describes enthalpy (H)? A) the total kinetic energy of a system B) the heat content of a chemical system C) the system's entropy D) the cell's energy equilibrium E) the condition of a cell that is not able to react
Answer: B Topic: Concept 8.2 Skill: Knowledge/Comprehension
64) Which statement best supports the hypothesis that glycolysis is an ancient metabolic pathway that originated before the last universal common ancestor of life on Earth? A) Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya. B) Glycolysis neither uses nor needs O2. C) Glycolysis is found in all eukaryotic cells. D) The enzymes of glycolysis are found in the cytosol rather than in a membrane-enclosed organelle. E) Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere.
Answer: A Topic: Concept 9.5 Skill: Synthesis/Evaluation
69) A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells? A) The mutant yeast will be unable to grow anaerobically. B) The mutant yeast will grow anaerobically only when given glucose. C) The mutant yeast will be unable to metabolize glucose. D) The mutant yeast will die because they cannot regenerate NAD+ from NAD. E) The mutant yeast will metabolize only fatty acids.
Answer: A Topic: Concept 9.5 Skill: Synthesis/Evaluation
70) You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave her body? A) It was released as CO2 and H2O. B) It was converted to heat and then released. C) It was converted to ATP, which weighs much less than fat. D) It was broken down to amino acids and eliminated from the body. E) It was converted to urine and eliminated from the body.
Answer: A Topic: Concept 9.6 Skill: Application/Analysis
77) What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions? A) glucose B) ethanol C) pyruvate D) lactic acid E) either ethanol or lactic acid
Answer: A Topic: Concept 9.6 Skill: Application/Analysis
80) Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy? A) glucose B) proteins C) fatty acids D) glucose, proteins, and fatty acids E) Such yeast cells will not be capable of catabolizing any food molecules, and will therefore die.
Answer: A Topic: Concept 9.6 Skill: Application/Analysis
23) Why is ATP an important molecule in metabolism? A) Its hydrolysis provides an input of free energy for exergonic reactions. B) It provides energy coupling between exergonic and endergonic reactions. C) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. D) Its terminal phosphate bond has higher energy than the other two. E) It is one of the four building blocks for DNA synthesis.
Answer: B Topic: Concept 8.3 Skill: Knowledge/Comprehension
26) Which of the following statements is true concerning catabolic pathways? A) They combine molecules into more energy-rich molecules. B) They supply energy, primarily in the form of ATP, for the cell's work. C) They are endergonic. D) They are spontaneous and do not need enzyme catalysis. E) They build up complex molecules such as protein from simpler compounds.
Answer: B Topic: Concept 8.3 Skill: Knowledge/Comprehension
35) During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction? A) -40 kcal/mol B) -20 kcal/mol C) 0 kcal/mol D) +20 kcal/mol E) +40 kcal/mol
Answer: B Topic: Concept 8.4 Skill: Application/Analysis
40) The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is A) oxidation of glucose to CO2 and water. B) the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers. C) the final transfer of electrons to oxygen. D) the proton-motive force across the inner mitochondrial membrane. E) the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.
Answer: D Topic: Concept 9.4 Skill: Knowledge/Comprehension
41) When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the A) formation of ATP. B) reduction of NAD+. C) restoration of the Na+/K+ balance across the membrane. D) creation of a proton-motive force. E) lowering of pH in the mitochondrial matrix.
Answer: D Topic: Concept 9.4 Skill: Knowledge/Comprehension
42) Where is ATP synthase located in the mitochondrion? A) cytosol B) electron transport chain C) outer membrane D) inner membrane E) mitochondrial matrix
Answer: D Topic: Concept 9.4 Skill: Knowledge/Comprehension
48) Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in A) all cells, but only in the presence of oxygen. B) only eukaryotic cells, in the presence of oxygen. C) only in mitochondria, using either oxygen or other electron acceptors. D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors. E) all cells, in the absence of respiration.
Answer: D Topic: Concept 9.4 Skill: Knowledge/Comprehension
58) Which metabolic pathway is common to both cellular respiration and fermentation? A) the oxidation of pyruvate to acetyl CoA B) the citric acid cycle C) oxidative phosphorylation D) glycolysis E) chemiosmosis
Answer: D Topic: Concept 9.5 Skill: Knowledge/Comprehension
73) Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur? A) in photosynthetic cells in the light, while photosynthesis occurs concurrently B) in nonphotosynthesizing cells only C) in cells that are storing glucose only D) in all cells all the time E) in photosynthesizing cells in the light and in other tissues in the dark
Answer: D Topic: Concept 9.6 Skill: Synthesis/Evaluation
13) Which of the following is true of metabolism in its entirety in all organisms? A) Metabolism depends on a constant supply of energy from food. B) Metabolism depends on an organism's adequate hydration. C) Metabolism uses all of an organism's resources. D) Metabolism consists of all the energy transformation reactions in an organism. E) Metabolism manages the increase of entropy in an organism.
Answer: D Topic: Concepts 8.1, 8.5 Skill: Synthesis/Evaluation
1) If photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen (18O), later analysis will show that all but one of the following compounds produced by the algae contain the 18O label. That one is A) 3-phosphoglycerate. B) glyceraldehyde 3-phosphate (G3P). C) glucose. D) ribulose bisphosphate (RuBP). E) O2.
Answer: E Topic: Concept 10.1 Skill: Application/Analysis
2) Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? A) CO2 and glucose B) H2O and O2 C) ADP, i, and NADP+ D) electrons and H+ E) ATP and NADPH
Answer: E Topic: Concept 10.1 Skill: Knowledge/Comprehension
3) Photosynthesis is not responsible for A) oxygen in the atmosphere. B) the ozone layer. C) most of the organic carbon on Earth's surface. D) atmospheric CO2. E) fossil fuels.
Answer: E Topic: Concept 10.1 Skill: Knowledge/Comprehension
11) Which of the events listed below occurs in the light reactions of photosynthesis? A) NADP is produced. B) NADPH is reduced to NADP+. C) Carbon dioxide is incorporated into PGA. D) ATP is phosphorylated to yield ADP. E) Light is absorbed and funneled to reaction-center chlorophyll a.
Answer: E Topic: Concept 10.2 Skill: Knowledge/Comprehension
35) In metabolic processes of cell respiration and photosynthesis, prosthetic groups such as heme and iron-sulfur complexes are encountered in components of the electron transport chain. What do they do? A) donate electrons B) act as reducing agents C) act as oxidizing agents D) transport protons within the mitochondria and chloroplasts E) both oxidize and reduce during electron transport
Answer: E Topic: Concept 10.2 Skill: Synthesis/Evaluation
9) Halobacterium has a photosynthetic membrane that is colored purple. Its photosynthetic action spectrum is exactly complementary (opposite to) the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb? A) red and yellow B) blue, green, and red C) green and yellow D) red and green E) blue and red
Answer: E Topic: Concept 10.2 Skill: Synthesis/Evaluation
41) What is the primary function of the Calvin cycle? A) use ATP to release carbon dioxide B) use NADPH to release carbon dioxide C) split water and release oxygen D) transport RuBP out of the chloroplast E) synthesize simple sugars from carbon dioxide
Answer: E Topic: Concept 10.3 Skill: Knowledge/Comprehension
1) Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? A) catalysis B) metabolism C) anabolism D) dehydration E) catabolism
Answer: E Topic: Concept 8.1 Skill: Knowledge/Comprehension
12) Which of the following is the smallest closed system? A) a cell B) an organism C) an ecosystem D) Earth E) the universe
Answer: E Topic: Concept 8.1 Skill: Knowledge/Comprehension
15) A system at chemical equilibrium A) consumes energy at a steady rate. B) releases energy at a steady rate. C) consumes or releases energy, depending on whether it is exergonic or endergonic. D) has zero kinetic energy. E) can do no work.
Answer: E Topic: Concept 8.2 Skill: Knowledge/Comprehension
24) When 10,000 molecules of ATP are hydrolyzed to ADP and i in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation? A) Cells are open systems, but a test tube is a closed system. B) Cells are less efficient at heat production than nonliving systems. C) The hydrolysis of ATP in a cell produces different chemical products than does the reaction in a test tube. D) The reaction in cells must be catalyzed by enzymes, but the reaction in a test tube does not need enzymes. E) Reactant and product concentrations in the test tube are different from those in the cell.
Answer: E Topic: Concept 8.3 Skill: Application/Analysis
30) What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA? A) The sugar molecule is different. B) The nitrogen-containing base is different. C) The number of phosphates is three instead of one. D) The number of phosphates is three instead of two. E) There is no difference.
Answer: E Topic: Concept 8.3 Skill: Knowledge/Comprehension
9) Where does glycolysis take place in eukaryotic cells? A) mitochondrial matrix B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) cytosol
Answer: E Topic: Concept 9.1 Skill: Knowledge/Comprehension
15) Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis? A) 0% B) 2% C) 10% D) 38% E) 100%
Answer: E Topic: Concept 9.2 Skill: Application/Analysis
23) Why is glycolysis described as having an investment phase and a payoff phase? A) It both splits molecules and assembles molecules. B) It attaches and detaches phosphate groups. C) It uses glucose and generates pyruvate. D) It shifts molecules from cytosol to mitochondrion. E) It uses stored ATP and then forms a net increase in ATP.
Answer: E Topic: Concept 9.2 Skill: Knowledge/Comprehension
26) During cellular respiration, acetyl CoA accumulates in which location? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix
Answer: E Topic: Concept 9.3 Skill: Knowledge/Comprehension
34) During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level? A) NAD+ B) NADH C) ATP D) ADP + i E) FADH2
Answer: E Topic: Concept 9.4 Skill: Knowledge/Comprehension
36) Inside an active mitochondrion, most electrons follow which pathway? A) glycolysis → NADH → oxidative phosphorylation → ATP → oxygen B) citric acid cycle → FADH2 → electron transport chain → ATP C) electron transport chain → citric acid cycle → ATP → oxygen D) pyruvate → citric acid cycle → ATP → NADH → oxygen E) citric acid cycle → NADH → electron transport chain → oxygen
Answer: E Topic: Concept 9.4 Skill: Knowledge/Comprehension
45) Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water? A) glycolysis B) fermentation C) oxidation of pyruvate to acetyl CoA D) citric acid cycle E) oxidative phosphorylation (chemiosmosis)
Answer: E Topic: Concept 9.4 Skill: Knowledge/Comprehension
46) Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration? A) 2 B) 4 C) 15 D) 30-32 E) 60-64
Answer: E Topic: Concept 9.4 Skill: Knowledge/Comprehension
55) Which catabolic processes may have been used by cells on ancient Earth before free oxygen became available? A) glycolysis and fermentation only B) glycolysis and the citric acid cycle only C) glycolysis, pyruvate oxidation, and the citric acid cycle D) oxidative phosphorylation only E) glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen
Answer: E Topic: Concept 9.4 Skill: Synthesis/Evaluation
63) An organism is discovered that thrives both in the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism A) must use a molecule other than oxygen to accept electrons from the electron transport chain. B) is a normal eukaryotic organism. C) is photosynthetic. D) is an anaerobic organism. E) is a facultative anaerobe.
Answer: E Topic: Concept 9.5 Skill: Application/Analysis
71) Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements correctly describes phosphofructokinase activity? A) It is inhibited by AMP. B) It is activated by ATP. C) It is activated by citrate, an intermediate of the citric acid cycle. D) It catalyzes the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate, an early step of glycolysis. E) It is an allosteric enzyme.
Answer: E Topic: Concept 9.6 Skill: Knowledge/Comprehension
75) What is the purpose of beta oxidation in respiration? A) oxidation of glucose B) oxidation of pyruvate C) feedback regulation D) control of ATP accumulation E) breakdown of fatty acids
Answer: E Topic: Concept 9.6 Skill: Knowledge/Comprehension
4) Where does the Calvin cycle take place? A) stroma of the chloroplast B) thylakoid membrane C) cytoplasm surrounding the chloroplast D) interior of the thylakoid (thylakoid space) E) outer membrane of the chloroplast
Answer: A Topic: Concept 10.1 Skill: Knowledge/Comprehension
32) Cyclic electron flow may be photoprotective (protective to light-induced damage). Which of the following experiments could provide information on this phenomenon? A) use mutated organisms that can grow but that cannot carry out cyclic flow of electrons and compare their abilities to photosynthesize in different light intensities against those of wild-type organisms B) use plants that can carry out both linear and cyclic electron flow, or only one or another of these processes, and compare their light absorbance at different wavelengths and different light intensities C) use bacteria that have only cyclic flow and look for their frequency of mutation damage at different light intensities D) use bacteria with only cyclic flow and measure the number and types of photosynthetic pigments they have in their membranes E) use plants with only photosystem I operative and measure how much damage occurs at different wavelengths
Answer: A Topic: Concept 10.2 Skill: Synthesis/Evaluation
49) The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find? A) The pH within the thylakoid is less than that of the stroma. B) The pH of the stroma is lower than that of the other two measurements. C) The pH of the stroma is higher than that of the thylakoid space but lower than that of the cytosol. D) The pH of the thylakoid space is higher than that anywhere else in the cell. E) There is no consistent relationship.
Answer: A Topic: Concept 10.3 Skill: Application/Analysis
40) Where do the enzymatic reactions of the Calvin cycle take place? A) stroma of the chloroplast B) thylakoid membranes C) matrix of the mitochondria D) cytosol around the chloroplast E) thylakoid space
Answer: A Topic: Concept 10.3 Skill: Knowledge/Comprehension
44) The NADPH required for the Calvin cycle comes from A) reactions initiated in photosystem I. B) reactions initiated in photosystem II. C) the citric acid cycle. D) glycolysis. E) oxidative phosphorylation.
Answer: A Topic: Concept 10.3 Skill: Knowledge/Comprehension
46) Which of the following statements best represents the relationships between the light reactions and the Calvin cycle? A) The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, i, and NADP+ to the light reactions. B) The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. C) The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP. D) The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split. E) There is no relationship between the light reactions and the Calvin cycle.
Answer: A Topic: Concept 10.3 Skill: Knowledge/Comprehension
52) In an experiment studying photosynthesis performed during the day, you provide a plant with radioactive carbon (14C) dioxide as a metabolic tracer. The 14C is incorporated first into oxaloacetate. The plant is best characterized as a A) C4 plant. B) C3 plant. C) CAM plant. D) heterotroph. E) chemoautotroph.
Answer: A Topic: Concept 10.4 Skill: Application/Analysis
58) Compared to C3 plants, C4 plants A) can continue to fix CO2 even at relatively low CO2 concentrations and high oxygen concentrations. B) have higher rates of photorespiration. C) do not use rubisco for carbon fixation. D) grow better under cool, moist conditions. E) make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria.
Answer: A Topic: Concept 10.4 Skill: Application/Analysis
54) CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they A) fix CO2 into organic acids during the night. B) fix CO2 into sugars in the bundle-sheath cells. C) fix CO2 into pyruvate in the mesophyll cells. D) use the enzyme phosphofructokinase, which outcompetes rubisco for CO2. E) use photosystem I and photosystem II at night.
Answer: A Topic: Concept 10.4 Skill: Knowledge/Comprehension
9) Which of the following types of reactions would decrease the entropy within a cell? A) anabolic reactions B) hydrolysis C) respiration D) digestion E) catabolic reactions
Answer: A Topic: Concept 8.1 Skill: Application/Analysis
10) Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellar eukaryotic organisms, A) has occurred in accordance with the laws of thermodynamics. B) has caused an increase in the entropy of the planet. C) has been made possible by expending Earth's energy resources. D) has occurred in accordance with the laws of thermodynamics, by expending Earth's energy resources and causing an increase in the entropy of the planet. E) violates the laws of thermodynamics because Earth is a closed system.
Answer: A Topic: Concept 8.1 Skill: Knowledge/Comprehension
3) Which of the following is a statement of the first law of thermodynamics? A) Energy cannot be created or destroyed. B) The entropy of the universe is decreasing. C) The entropy of the universe is constant. D) Kinetic energy is stored energy that results from the specific arrangement of matter. E) Energy cannot be transferred or transformed.
Answer: A Topic: Concept 8.1 Skill: Knowledge/Comprehension
20) A chemical reaction that has a positive ΔG is correctly described as A) endergonic. B) endothermic. C) enthalpic. D) spontaneous. E) exothermic.
Answer: A Topic: Concept 8.2 Skill: Knowledge/Comprehension
43) Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses? A) in or near the active site B) at an allosteric site C) at a cofactor binding site D) in regions of the protein that determine packaging into the virus capsid E) such mutations could occur anywhere with equal probability
Answer: A Topic: Concept 8.4 Skill: Application/Analysis
31) Which of the following statements is true about enzyme-catalyzed reactions? A) The reaction is faster than the same reaction in the absence of the enzyme. B) The free energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme. C) The reaction always goes in the direction toward chemical equilibrium. D) Enzyme-catalyzed reactions require energy to activate the enzyme. E) Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions.
Answer: A Topic: Concept 8.4 Skill: Knowledge/Comprehension
42) In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur? A) The ATP must first have to attach to the tRNA. B) The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme. C) The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase. D) The tRNA molecule must have to alter its shape in order to be able to fit into the active site with the other two molecules. E) The 3' end of the tRNA must have to be cleaved before it can have an attached amino acid.
Answer: B Topic: Concept 8.4 Skill: Synthesis/Evaluation
47) The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as A) metabolic inhibition. B) feedback inhibition. C) allosteric inhibition. D) noncooperative inhibition. E) reversible inhibition.
Answer: B Topic: Concept 8.5 Skill: Knowledge/Comprehension
52) Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity? A) cessation of cellular protein synthesis B) localization of enzymes into specific organelles or membranes C) exporting enzymes out of the cell D) connecting enzymes into large aggregates E) hydrophobic interactions
Answer: B Topic: Concept 8.5 Skill: Knowledge/Comprehension
1) What is the term for metabolic pathways that release stored energy by breaking down complex molecules? A) anabolic pathways B) catabolic pathways C) fermentation pathways D) thermodynamic pathways E) bioenergetic pathways
Answer: B Topic: Concept 9.1 Skill: Knowledge/Comprehension
11) The oxygen consumed during cellular respiration is involved directly in which process or event? A) glycolysis B) accepting electrons at the end of the electron transport chain C) the citric acid cycle D) the oxidation of pyruvate to acetyl CoA E) the phosphorylation of ADP to form ATP
Answer: B Topic: Concept 9.1 Skill: Knowledge/Comprehension
12) Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent? A) electron transport B) glycolysis C) the citric acid cycle D) oxidative phosphorylation E) chemiosmosis
Answer: B Topic: Concept 9.1 Skill: Knowledge/Comprehension
13) An electron loses potential energy when it A) shifts to a less electronegative atom. B) shifts to a more electronegative atom. C) increases its kinetic energy. D) increases its activity as an oxidizing agent. E) moves further away from the nucleus of the atom.
Answer: B Topic: Concept 9.1 Skill: Knowledge/Comprehension
2) The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction A) gains electrons and gains potential energy. B) loses electrons and loses potential energy. C) gains electrons and loses potential energy. D) loses electrons and gains potential energy. E) neither gains nor loses electrons, but gains or loses potential energy.
Answer: B Topic: Concept 9.1 Skill: Knowledge/Comprehension
4) Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? A) The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. B) Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O). C) The oxidation of organic compounds can be used to make ATP. D) The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds. E) The covalent bond in O2 is unstable and easily broken by electrons from organic molecules.
Answer: B Topic: Concept 9.1 Skill: Knowledge/Comprehension
19) Starting with one molecule of glucose, the energy-containing products of glycolysis are A) 2 NAD+, 2 pyruvate, and 2 ATP. B) 2 NADH, 2 pyruvate, and 2 ATP. C) 2 FADH2, 2 pyruvate, and 4 ATP. D) 6 CO2, 2 ATP, and 2 pyruvate. E) 6 CO2, 30 ATP, and 2 pyruvate.
Answer: B Topic: Concept 9.2 Skill: Knowledge/Comprehension
20) In glycolysis, for each molecule of glucose oxidized to pyruvate A) two molecules of ATP are used and two molecules of ATP are produced. B) two molecules of ATP are used and four molecules of ATP are produced. C) four molecules of ATP are used and two molecules of ATP are produced. D) two molecules of ATP are used and six molecules of ATP are produced. E) six molecules of ATP are used and six molecules of ATP are produced.
Answer: B Topic: Concept 9.2 Skill: Knowledge/Comprehension
30) During aerobic respiration, electrons travel downhill in which sequence? A) food → citric acid cycle → ATP → NAD+ B) food → NADH → electron transport chain → oxygen C) glucose → pyruvate → ATP → oxygen D) glucose → ATP → electron transport chain → NADH E) food → glycolysis → citric acid cycle → NADH → ATP
Answer: B Topic: Concept 9.3 Skill: Application/Analysis
28) Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? A) glycolysis and the oxidation of pyruvate to acetyl CoA B) oxidation of pyruvate to acetyl CoA and the citric acid cycle C) the citric acid cycle and oxidative phosphorylation D) oxidative phosphorylation and fermentation E) fermentation and glycolysis
Answer: B Topic: Concept 9.3 Skill: Knowledge/Comprehension
43) It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of the following processes could still be carried on by this isolated inner membrane? A) the citric acid cycle B) oxidative phosphorylation C) glycolysis and fermentation D) reduction of NAD+ E) both the citric acid cycle and oxidative phosphorylation
Answer: B Topic: Concept 9.4 Skill: Application/Analysis
47) The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of A) active transport. B) an endergonic reaction coupled to an exergonic reaction. C) a reaction with a positive ΔG . D) osmosis. E) allosteric regulation.
Answer: B Topic: Concept 9.4 Skill: Application/Analysis
33) In cellular respiration, the energy for most ATP synthesis is supplied by A) high energy phosphate bonds in organic molecules. B) a proton gradient across a membrane. C) converting oxygen to ATP. D) transferring electrons from organic molecules to pyruvate. E) generating carbon dioxide and oxygen in the electron transport chain.
Answer: B Topic: Concept 9.4 Skill: Knowledge/Comprehension
29) A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don't often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10-7 while the concentration in the SR is 10-2, then how is the ATPase acting? A) ATPase activity must be powering an inflow of calcium from the outside of the cell into the SR. B) ATPase activity must be transferring i to the SR to enable this to occur. C) ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient. D) ATPase activity must be opening a channel for the calcium ions to diffuse back into the SR along the concentration gradient. E) ATPase activity must be routing calcium ions from the SR to the cytosol, and then to the cell's environment.
Answer: C Topic: Concept 8.3 Skill: Synthesis/Evaluation
33) A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because A) the starch solution has less free energy than the sugar solution. B) the hydrolysis of starch to sugar is endergonic. C) the activation energy barrier for this reaction cannot be surmounted. D) starch cannot be hydrolyzed in the presence of so much water. E) starch hydrolysis is nonspontaneous.
Answer: C Topic: Concept 8.4 Skill: Application/Analysis
39) Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? A) denaturization of the enzyme B) allosteric inhibition C) competitive inhibition D) saturation of the enzyme activity E) insufficient cofactors
Answer: C Topic: Concept 8.4 Skill: Application/Analysis
45) When you have a severe fever, what grave consequence may occur if the fever is not controlled? A) destruction of your enzymes' primary structure B) removal of amine groups from your proteins C) change in the tertiary structure of your enzymes D) removal of the amino acids in active sites of your enzymes E) binding of your enzymes to inappropriate substrates
Answer: C Topic: Concept 8.4 Skill: Application/Analysis
55) How might an amino acid change at a site distant from the active site of the enzyme alter the enzyme's substrate specificity? A) by changing the enzyme's stability B) by changing the enzyme's location in the cell C) by changing the shape of the protein D) by changing the enzyme's pH optimum E) an amino acid change away from the active site cannot alter the enzyme's substrate specificity
Answer: C Topic: Concept 8.4 Skill: Application/Analysis
54) In experimental tests of enzyme evolution, where a gene encoding an enzyme is subjected to multiple cycles of random mutagenesis and selection for altered substrate specificity, the resulting enzyme had multiple amino acid changes associated with altered substrate specificity. Where in the enzyme were these amino acid changes located? A) only in the active site B) only in the active site or near the active site C) in or near the active site and at surface sites away from the active site D) only at surface sites away from the active site E) only in the hydrophobic interior of the folded protein
Answer: C Topic: Concept 8.4 Skill: Knowledge/Comprehension
50) Which of the following is an example of cooperativity? A) the binding of an end product of a metabolic pathway to the first enzyme that acts in the pathway B) one enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway C) a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three D) the effect of increasing temperature on the rate of an enzymatic reaction E) binding of an ATP molecule along with one of the substrate molecules in an active site
Answer: C Topic: Concept 8.5 Skill: Application/Analysis
48) Which of the following statements describes enzyme cooperativity? A) A multienzyme complex contains all the enzymes of a metabolic pathway. B) A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway. C) A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits. D) Several substrate molecules can be catalyzed by the same enzyme. E) A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.
Answer: C Topic: Concept 8.5 Skill: Knowledge/Comprehension
53) An important group of peripheral membrane proteins are enzymes such as the phospholipases that cleave the head groups of phospholipids. What properties must these enzymes exhibit? A) resistance to degradation B) independence from cofactor interaction C) water solubility D) lipid solubility E) membrane-spanning domains
Answer: C Topic: Concept 8.5 Skill: Synthesis/Evaluation
6) When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes A) hydrolyzed. B) hydrogenated. C) oxidized. D) reduced. E) an oxidizing agent.
Answer: C Topic: Concept 9.1 Skill: Knowledge/Comprehension
7) When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes A) dehydrogenated. B) oxidized. C) reduced. D) redoxed. E) hydrolyzed.
Answer: C Topic: Concept 9.1 Skill: Knowledge/Comprehension
22) Which kind of metabolic poison would most directly interfere with glycolysis? A) an agent that reacts with oxygen and depletes its concentration in the cell B) an agent that binds to pyruvate and inactivates it C) an agent that closely mimics the structure of glucose but is not metabolized D) an agent that reacts with NADH and oxidizes it to NAD+ E) an agent that blocks the passage of electrons along the electron transport chain
Answer: C Topic: Concept 9.2 Skill: Application/Analysis
16) During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is A) transferred to ADP, forming ATP. B) transferred directly to ATP. C) retained in the two pyruvates. D) stored in the NADH produced. E) used to phosphorylate fructose to form fructose 6-phosphate.
Answer: C Topic: Concept 9.2 Skill: Knowledge/Comprehension
17) In addition to ATP, what are the end products of glycolysis? A) CO2 and H2O B) CO2 and pyruvate C) NADH and pyruvate D) CO2 and NADH E) H2O, FADH2, and citrate
Answer: C Topic: Concept 9.2 Skill: Knowledge/Comprehension
18) The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed? A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis. B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat. C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. D) There is no CO2 or water produced as products of glycolysis. E) Glycolysis consists of many enzymatic reactions, each of which extracts some energy from the glucose molecule.
Answer: C Topic: Concept 9.2 Skill: Synthesis/Evaluation
49) If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized by carbon dioxide and water, how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? A) 0 B) 1 C) 12 D) 14 E) 15
Answer: C Topic: Concept 9.4 Skill: Application/Analysis
51) In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A) It allows for an increased rate of glycolysis. B) It allows for an increased rate of the citric acid cycle. C) It increases the surface for oxidative phosphorylation. D) It increases the surface for substrate-level phosphorylation. E) It allows the liver cell to have fewer mitochondria.
Answer: C Topic: Concept 9.4 Skill: Application/Analysis
52) Brown fat cells produce a protein called thermogenin in their mitochondrial inner membrane. Thermogenin is a channel for facilitated transport of protons across the membrane. What will occur in the brown fat cells when they produce thermogenin? A) ATP synthesis and heat generation will both increase. B) ATP synthesis will increase, and heat generation will decrease. C) ATP synthesis will decrease, and heat generation will increase. D) ATP synthesis and heat generation will both decrease. E) ATP synthesis and heat generation will stay the same.
Answer: C Topic: Concept 9.4 Skill: Application/Analysis
53) In a mitochondrion, if the matrix ATP concentration is high, and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then A) ATP synthase will increase the rate of ATP synthesis. B) ATP synthase will stop working. C) ATP synthase will hydrolyze ATP and pump protons into the intermembrane space. D) ATP synthase will hydrolyze ATP and pump protons into the matrix.
Answer: C Topic: Concept 9.4 Skill: Application/Analysis
32) Where are the proteins of the electron transport chain located? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix
Answer: C Topic: Concept 9.4 Skill: Knowledge/Comprehension
37) During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from? A) carbon dioxide (CO2) B) glucose (C6H12O6) C) molecular oxygen (O2) D) pyruvate (C3H3O3-) E) lactate (C3H5O3-)
Answer: C Topic: Concept 9.4 Skill: Knowledge/Comprehension
44) How many oxygen molecules (O2) are required each time a molecule of glucose (C6H12O6) is completely oxidized to carbon dioxide and water via aerobic respiration,? A) 1 B) 3 C) 6 D) 12 E) 30
Answer: C Topic: Concept 9.4 Skill: Knowledge/Comprehension
54) In prokaryotes, the respiratory electron transport chain is located A) in the mitochondrial inner membrane. B) in the mitochondrial outer membrane. C) in the plasma membrane. D) in the cytoplasm. E) in the bacterial outer membrane.
Answer: C Topic: Concept 9.4 Skill: Knowledge/Comprehension
62) One function of both alcohol fermentation and lactic acid fermentation is to A) reduce NAD+ to NADH. B) reduce FAD+ to FADH2. C) oxidize NADH to NAD+. D) reduce FADH2 to FAD+. E) do none of the above.
Answer: C Topic: Concept 9.5 Skill: Application/Analysis
66) When an individual is exercising heavily and when the muscle becomes oxygen-deprived, muscle cells convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells? A) It is converted to NAD+. B) It produces CO2 and water. C) It is taken to the liver and converted back to pyruvate. D) It reduces FADH2 to FAD+. E) It is converted to alcohol.
Answer: C Topic: Concept 9.5 Skill: Knowledge/Comprehension
76) Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle? A) pyruvate B) malate or fumarate C) acetyl CoA D) α-ketoglutarate E) succinyl CoA
Answer: C Topic: Concept 9.6 Skill: Knowledge/Comprehension
22) For the hydrolysis of ATP to ADP + i, the free energy change is -7.3 kcal/mol under standard conditions (1 M concentration of both reactants and products). In the cellular environment, however, the free energy change is about -13 kcal/mol. What can we conclude about the free energy change for the formation of ATP from ADP and i under cellular conditions? A) It is +7.3 kcal/mol. B) It is less than +7.3 kcal/mol. C) It is about +13 kcal/mol. D) It is greater than +13 kcal/mol. E) The information given is insufficient to deduce the free energy change.
Answer: C Topic: Concepts 8.2, 8.3 Skill: Application/Analysis
5) In any ecosystem, terrestrial or aquatic, what group(s) is (are) always necessary? A) autotrophs and heterotrophs B) producers and primary consumers C) photosynthesizers D) autotrophs E) green plants
Answer: D Topic: Concept 10.1 Skill: Synthesis/Evaluation
17) Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes? A) the splitting of water B) the absorption of light energy by chlorophyll C) the flow of electrons from photosystem II to photosystem I D) the synthesis of ATP E) the reduction of NADP+
Answer: D Topic: Concept 10.2 Skill: Application/Analysis
38) In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + i to ATP? A) energy released as electrons flow through the electron transport system B) energy released from substrate-level phosphorylation C) energy released from movement of protons through ATP synthase, against the electrochemical gradient D) energy released from movement of protons through ATP synthase, down the electrochemical gradient E) No external source of energy is required because the reaction is exergonic.
Answer: D Topic: Concept 9.4 Skill: Knowledge/Comprehension
39) A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask. A) The dissolved oxygen in the flask with algae will always be higher. B) The dissolved oxygen in the flask with algae will always be lower. C) The dissolved oxygen in the flask with algae will be higher in the light, but the same in the dark. D) The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark. E) The dissolved oxygen in the flask with algae will not be different from the control flask at any time.
Answer: D Topic: Concept 10.2 Skill: Application/Analysis
12) Which statement describes the functioning of photosystem II? A) Light energy excites electrons in the thylakoid membrane electron transport chain. B) Photons are passed along to a reaction-center chlorophyll. C) The P680 chlorophyll donates a pair of protons to NADP+, which is thus converted to NADPH. D) The electron vacancies in P680+ are filled by electrons derived from water. E) The splitting of water yields molecular carbon dioxide as a by-product.
Answer: D Topic: Concept 10.2 Skill: Knowledge/Comprehension
20) In a plant cell, where are the ATP synthase complexes located? A) thylakoid membrane only B) plasma membrane only C) inner mitochondrial membrane only D) thylakoid membrane and inner mitochondrial membrane E) thylakoid membrane and plasma membrane
Answer: D Topic: Concept 10.2 Skill: Knowledge/Comprehension
27) The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during A) photosynthesis. B) respiration. C) both photosynthesis and respiration. D) neither photosynthesis nor respiration. E) photorespiration.
Answer: D Topic: Concept 10.2 Skill: Knowledge/Comprehension
34) In thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. Therefore, the catalytic "knobs" of ATP synthase would be located A) on the side facing the thylakoid space. B) on the ATP molecules themselves. C) on the pigment molecules of photosystem I and photosystem II. D) on the stromal side of the membrane. E) built into the center of the thylakoid stack (granum).
Answer: D Topic: Concept 10.2 Skill: Knowledge/Comprehension
30) P680+ is said to be the strongest biological oxidizing agent. Why? A) It is the receptor for the most excited electron in either photosystem. B) It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system. C) It transfers its electrons to reduce NADP+ to NADPH. D) This molecule has a stronger attraction for electrons than oxygen, to obtain electrons from water. E) It has a positive charge.
Answer: D Topic: Concept 10.2 Skill: Synthesis/Evaluation
48) In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle? A) addition of a pair of electrons from NADPH B) inactivation of RuBP carboxylase enzyme C) regeneration of ATP from ADP D) regeneration of RuBP E) regeneration of NADP+
Answer: D Topic: Concept 10.3 Skill: Application/Analysis
43) In a plant leaf, the reactions that produce NADH occur in A) the light reactions alone. B) the Calvin cycle alone. C) both the light reactions and the Calvin cycle. D) neither the light reactions nor the Calvin cycle. E) the chloroplast, but is not part of photosynthesis.
Answer: D Topic: Concept 10.3 Skill: Knowledge/Comprehension
50) The phylogenetic distribution of the enzyme rubisco is limited to A) C3 plants only. B) C3 and C4 plants. C) all photosynthetic eukaryotes. D) all known photoautotrophs, both bacterial and eukaryotic. E) all living cells.
Answer: D Topic: Concept 10.3 Skill: Knowledge/Comprehension
47) Three "turns" of the Calvin cycle generate a "surplus" molecule of glyceraldehyde 3-phosphate (G3P). Which of the following is a consequence of this? A) Formation of a molecule of glucose would require nine "turns." B) G3P more readily forms sucrose and other disaccharides than it does monosaccharides. C) Some plants would not taste sweet to us. D) The formation of sucrose and starch in plants involves assembling G3P molecules, with or without further rearrangements. E) Plants accumulate and store G3P.
Answer: D Topic: Concept 10.3 Skill: Synthesis/Evaluation
57) If plant gene alterations cause the plants to be deficient in photorespiration, what would most probably occur? A) Photosynthetic efficiency would be reduced at low light intensities. B) Cells would carry on the Calvin cycle at a much slower rate. C) Less ATP would be generated. D) There would be more light-induced damage to the cells. E) Less oxygen would be produced.
Answer: D Topic: Concept 10.4 Skill: Knowledge/Comprehension
11) Which of the following is an example of potential rather than kinetic energy? A) the muscle contractions of a person mowing grass B) water rushing over Niagara Falls C) light flashes emitted by a firefly D) a molecule of glucose E) the flight of an insect foraging for food
Answer: D Topic: Concept 8.1 Skill: Knowledge/Comprehension
6) Whenever energy is transformed, there is always an increase in the A) free energy of the system. B) free energy of the universe. C) entropy of the system. D) entropy of the universe. E) enthalpy of the universe.
Answer: D Topic: Concept 8.1 Skill: Knowledge/Comprehension
8) Which of the following statements is representative of the second law of thermodynamics? A) Conversion of energy from one form to another is always accompanied by some gain of free energy. B) Heat represents a form of energy that can be used by most organisms to do work. C) Without an input of energy, organisms would tend toward decreasing entropy. D) Cells require a constant input of energy to maintain their high level of organization. E) Every energy transformation by a cell decreases the entropy of the universe.
Answer: D Topic: Concept 8.1 Skill: Knowledge/Comprehension
39) Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix
Answer: D Topic: Concept 9.4 Skill: Knowledge/Comprehension
5) Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics? A) Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time. B) Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is exactly balanced by an increase in the entropy of the universe. C) Living organisms do not follow the laws of thermodynamics. D) As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth. E) Living organisms are able to transform energy into entropy.
Answer: D Topic: Concept 8.1 Skill: Synthesis/Evaluation
7) Which of the following statements is a logical consequence of the second law of thermodynamics? A) If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe. B) If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe. C) Every energy transfer requires activation energy from the environment. D) Every chemical reaction must increase the total entropy of the universe. E) Energy can be transferred or transformed, but it cannot be created or destroyed.
Answer: D Topic: Concept 8.1 Skill: Synthesis/Evaluation
17) Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell? A) a reaction in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium B) a chemical reaction in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's surroundings C) an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment D) a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway E) no possibility of having chemical equilibrium in any living cell
Answer: D Topic: Concept 8.2 Skill: Synthesis/Evaluation
28) When ATP releases some energy, it also releases inorganic phosphate. What purpose does this serve (if any) in the cell? A) The phosphate is released as an excretory waste. B) The phosphate can only be used to regenerate more ATP. C) The phosphate can be added to water and excreted as a liquid. D) The phosphate may be incorporated into any molecule that contains phosphate. E) It enters the nucleus to affect gene expression.
Answer: D Topic: Concept 8.3 Skill: Application/Analysis
27) When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated? A) It is used to power yet more cellular work. B) It is used to store energy as more ATP. C) It is used to generate ADP from nucleotide precursors. D) It is lost to the environment. E) It is transported to specific organs such as the brain.
Answer: D Topic: Concept 8.3 Skill: Knowledge/Comprehension
41) Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n) A) competitive inhibitor of the enzyme. B) noncompetitive inhibitor of the enzyme. C) allosteric activator of the enzyme. D) cofactor necessary for enzyme activity. E) coenzyme derived from a vitamin.
Answer: D Topic: Concept 8.4 Skill: Application/Analysis
37) According to the induced fit hypothesis of enzyme catalysis, which of the following is correct? A) The binding of the substrate depends on the shape of the active site. B) Some enzymes change their structure when activators bind to the enzyme. C) A competitive inhibitor can outcompete the substrate for the active site. D) The binding of the substrate changes the shape of the enzyme's active site. E) The active site creates a microenvironment ideal for the reaction.
Answer: D Topic: Concept 8.4 Skill: Knowledge/Comprehension
40) Which of the following is true of enzymes? A) Nonprotein cofactors alter the substrate specificity of enzymes. B) Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered. C) Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers. E) Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.
Answer: D Topic: Concept 8.4 Skill: Knowledge/Comprehension
38) Mutations that result in single amino acid substitutions in an enzyme A) can have no effect on the activity or properties of the enzyme. B) will almost always destroy the activity of the enzyme. C) will often cause a change in the substrate specificity of the enzyme. D) may affect the physicochemical properties of the enzyme such as its optimal temperature and pH. E) may, in rare cases, cause the enzyme to run reactions in reverse.
Answer: D Topic: Concept 8.4 Skill: Synthesis/Evaluation
49) Allosteric enzyme regulation is usually associated with A) lack of cooperativity. B) feedback inhibition. C) activating activity. D) an enzyme with more than one subunit. E) the need for cofactors.
Answer: D Topic: Concept 8.5 Skill: Knowledge/Comprehension
14) Why are carbohydrates and fats considered high energy foods? A) They have a lot of oxygen atoms. B) They have no nitrogen in their makeup. C) They can have very long carbon skeletons. D) They have a lot of electrons associated with hydrogen. E) They are easily reduced.
Answer: D Topic: Concept 9.1 Skill: Knowledge/Comprehension
21) A molecule that is phosphorylated A) has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate. B) has a decreased chemical reactivity; it is less likely to provide energy for cellular work. C) has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate. D) has an increased chemical potential energy; it is primed to do cellular work. E) has less energy than before its phosphorylation and therefore less energy for cellular work.
Answer: D Topic: Concept 9.2 Skill: Synthesis/Evaluation
31) What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source? A) 1/6 B) 1/3 C) 1/2 D) 2/3 E) 100/100
Answer: D Topic: Concept 9.3 Skill: Application/Analysis
25) Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate? A) lactate B) glyceraldehydes-3-phosphate C) oxaloacetate D) acetyl CoA E) citrate
Answer: D Topic: Concept 9.3 Skill: Knowledge/Comprehension
74) In vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue? A) to increase the rate of oxidative phosphorylation from its few mitochondria B) to allow the animals to regulate their metabolic rate when it is especially hot C) to increase the production of ATP D) to allow other membranes of the cell to perform mitochondrial functions E) to regulate temperature by converting most of the energy from NADH oxidation to heat
Answer: E Topic: Concept 9.6 Skill: Synthesis/Evaluation
