Test 2 Question
Once they have been processed through the citric acid cycle, the acetyl-CoA molecules from a single glucose molecule produce: 2 ATP, 6 NADH, 4 CO2. 6 FADH2, 2 ATP, 6 CO2. 4 CO2, 6 FADH2, 2 ATP. 6 NADH, 6 GTP. 6 GTP, 6 FADH2.
Correct: 2 ATP, 6 NADH, 4 CO2
After pyruvate oxidation, the chemical energy of how many carbons of the original glucose molecule is converted to chemical energy in the form of ATP in the remaining steps of cellular respiration? Please choose the correct answer from the following choices, and then select the submit answer button. 1 2 3 4
Correct: 4
Beta-oxidation of fatty acids does not directly produce: electrons transferred to NAD+. electrons transferred to FADH.. acetyl-CoA. ATP.
Correct: ATP.
Xanthophyll pigments: Please choose the correct answer from the following choices, and then select the submit answer button. prevent formation of reactive oxygen species. absorb light energy.. convert light energy into heat. reflect yellow light. All of these choices are correct.
Correct: All of these choices are correct
Many photosynthetic prokaryotes are capable of cyclic electron transport only. It is likely that such organisms can _____ but not _____. produce ATP; reduce CO2 produce NADPH; reduce CO2 reduce CO2; synthesize carbohydrates produce ATP; reduce H2O produce NADPH; oxidize H2O
produce ATP; reduce CO2
Organisms with only one photosystem cannot: produce O2. reduce H2O. reduce NADP+. reduce CO2. oxidize H2S.
produce O2..
In eukaryotic cells, the oxidation of pyruvate occurs in: the nucleus. the cytoplasm. the endoplasmic reticulum. the matrix of the mitochondria. vacuoles
the matrix of the mitochondria
The breakdown of fatty acids takes place by a process called: oxidative phosphorylation. glycolysis. beta-oxidation. pyruvate oxidation. electron transport.
Correct: beta-oxidation.
Cellular respiration is a series of _____ reactions. catabolic phosphorylation glycolytic carboxylation anabolic
Correct: catabolic
Which of the following is a product of the breakdown of lipids? (Select all that apply.) NADH glycerol FADH2 acetyl-CoA
NADH glycerol FADH2 acetyl-CoA
which of the following is a by-product of photosynthesis?
O2
How many CO2 molecules must enter the Calvin cycle for each molecule of triose phosphate that can be exported from the chloroplast?
3
Assuming that all is working properly, which of the following is at a higher energy level? An excited-state reaction center chlorophyll An excited-state antenna chlorophyll
An excited-state antenna chlorophyll
At the end of glycolysis, but before the subsequent steps in cellular respiration, which molecules contain some of the energy held in the original glucose molecule?
At the end of glycolysis, the energy in the original glucose molecule is contained in pyruvate, ATP, and NADH
At the end of the citric acid cycle, but before the subsequent steps of cellular respiration, which molecules contain the energy held in the original glucose molecule?
At the end of the citric acid cycle, the energy in the original glucose molecule is held in ATP, NADH, and FADH2.
Which of the following is/are rubisco substrates? CO2, O2, and RuBP CO2 O2 CO2 and RuBP RuBP
CO2, O2, and RuBP
Imagine that a eukaryotic cell carries a mutation impairing its ability to phosphorylate glucose during glycolysis. What is a likely result of this mutation? Please choose the correct answer from the following choices, and then select the submit answer button. High (possibly toxic) levels of glucose would accumulate in the cell. Without the phosphorylation of glucose, glycolysis would consist entirely of exergonic reactions. Because phosphorylation stabilizes glucose, glucose would spontaneously form pyruvate. Glucose could move out of the cell, slowing cellular respiration. More pyruvate would be formed at the end of glycolysis.
Correct: Glucose could move out of the cell, slowing cellular respiration.
You may be familiar with the story of Philippides, the famous Greek runner who ran the first marathon and then died after completing his run. Based on what you know of aerobic respiration and fermentation, why might Philippides have died? His muscles may have produced toxic levels of lactic acid, causing his blood to become more acidic. His muscles may have produced toxic levels of lactic acid, causing his blood to become more basic. His muscles may have produced toxic levels of ethanol, causing his blood to become more acidic. His muscles may have produced toxic levels of ethanol, causing his blood to become more basic. His muscles may have produced toxic levels of both ethanol and lactic acid, causing his blood to become more acidic.
Correct: His muscles may have produced toxic levels of lactic acid, causing his blood to become more acidic.
Which of the following correctly characterizes the F1 subunit of ATP synthase? It is embedded in the inner mitochondrial membrane. It forms the channel through which protons flow. It is the catalytic unit that synthesizes ATP. None of the other answer options is correct.
Correct: It is the catalytic unit that synthesizes ATP.
When a single pyruvate is converted to acetyl-CoA, the other products of the reaction are: NADH and CO2 ATP and NADH. CO2 and ATP. FADH2 and ATP. Pi and FADH2.
Correct: NADH and CO2
The inputs to glycolysis do not include: NADH. NAD+. glucose. ADP. Pi.
Correct: NADH.
Which of the following statements is true regarding pyruvate oxidation? Please choose the correct answer from the following choices, and then select the submit answer button. Pyruvate oxidation ends with the oxidation of an acetyl group, which forms CO2 Like glycolysis, pyruvate oxidation is carried out in the mitochondria. Pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis. Pyruvate oxidation directly follows the citric acid cycle during cellular respiration.
Correct: Pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis.
Which of the following compounds is required for the carboxylation step of the Calvin cycle? ATP 3-PGA RuBP NADPH ATP and NADPH
Correct: RuBP
The regeneration of RuBP typically limits the rate of photosynthesis under low light intensities. This is because: Please choose the correct answer from the following choices, and then select the submit answer button. RuBP regeneration requires ADP. RuBP regeneration requires ATP. RuBP regeneration is part of the "dark reactions." photosynthesis occurs only in high light. None of the answer options is correct.
Correct: RuBP regeneration requires ATP
The only known "solution" to the loss of efficiency caused by the oxygenation of RuBP by rubisco is to raise the concentration of CO2 in the cell using energy from ATP. Which of the following is most correct of such plants? They do not produce O2. They are tolerant of shade. They are often found in bright, sunny habitats. They do not produce reactive O2 species. They require high CO2 levels.
Correct: They are often found in bright, sunny habitats.
Which of the following is true concerning the Calvin cycle and light-harvesting reactions of photosynthesis? They take place in different organelles. They take place in different compartments of the same organelle. They take place in different types of cells in the plant None of the other answer options is correct.
Correct: They take place in different compartments of the same organelle
Weak covalent bonds, such as ones in carbohydrates and lipids, have: little kinetic energy. a lot of kinetic energy. little potential energy. a lot of potential energy.
Correct: a lot of potential energy.
Energy released by transferring electrons along the electron transport chain is stored as potential energy in the form of: ATP. redox couples. ATP synthase. a proton gradient. coenzyme Q.
Correct: a proton gradient.
From its ground state, photosystem II can: pull electrons from H2O. pull protons from H2O. pass electrons to photosystem I. emit light energy. absorb light energy.
Correct: absorb light energy.
Lactic acid fermentation occurs in: Select all that apply. Please choose the correct answer from the following choices, and then select the submit answer button. bacteria and animals. plants and bacteria. fungi and bacteria. animals and plants. animals and fungi.
Correct: bacteria and animals
Imagine that you discover a microbial deep-sea organism that can derive energy from (inorganic) hydrogen gas (H2). However, this microbe can also synthesize organic compounds from carbon-containing inorganic molecules in the ocean. This microbe is a: phototroph. photoautotroph. chemoautotroph. chemoheterotroph. photoheterotroph.
Correct: chemoautotroph
Escherichia coli bacteria in your colon are categorized as: Please choose the correct answer from the following choices, and then select the submit answer button. photoheterotrophs. photoautotrophs. chemoautotrophs. chemoheterotrophs.
Correct: chemoheterotrophs.
Which of the following lowers the efficiency of plants' conversion of sunlight into chemical energy? cold temperatures and bright sunlight the presence of antioxidants in the chloroplasts the presence of carotenoids in the chloroplasts increased carbon dioxide levels
Correct: cold temperatures and bright sunlight
In the Calvin cycle, NADPH is: Please choose the correct answer from the following choices, and then select the submit answer button. oxidized and reduced. oxidized. reduced.
Correct: oxidized.
In cellular respiration, glucose is _____ to CO2 and oxygen is _____ to water. phosphorylated; deoxygenated deoxygenated; phosphorylated oxidized; reduced oxidized; oxidized reduced; oxidized
Correct: oxidized; reduced
An electron from NADH entering the electron transport chain would travel among components of the chain in what sequence? Please choose the correct answer from the following choices, and then select the submit answer button. - complex II, cytochrome C, complex IV, cytochrome C, oxygen - complex I, coenzyme Q, complex III, cytochrome C, ATP synthase, oxygen - complex I, coenzyme Q, complex III, cytochrome C, complex IV, oxygen - complex II, coenzyme Q, complex IV, cytochrome C, ATP synthase, oxygen - complex I, coenzyme Q, complex II, cytochrome C, complex III, coenzyme Q, complex IV, cytochrome C, oxygen
Correct: complex I, coenzyme Q, complex III, cytochrome C, complex IV, oxygen
Chemicals called uncouplers can make membranes permeable to small molecules and ions. What effect might un-couplers have on photosynthesis? decreased ATP production because the proton gradient would increase increased ATP production because cyclic electron transport would increase decreased NADPH production because the proton gradient would increase decreased ATP production because the proton gradient would decrease decreased NADPH production because the proton gradient would decrease
Correct: decreased ATP production because the proton gradient would decrease
Phosphorylating glucose during phase 1 of glycolysis: releases phosphorylated glucose from cells. destabilizes the glucose molecule so that it can be broken down in phase 2. provides electrons to reduce NAD+ in phase 3. provides electrons to reduce FADH in phase 3.
Correct: destabilizes the glucose molecule so that it can be broken down in phase 2.
How does the metabolism occurring in chloroplasts differ from that of mitochondria? Please choose the correct answer from the following choices, and then select the submit answer button. different electron sources different proton sources different electron acceptors different electron acceptors and electron sources None of the other answer options is correct
Correct: different electron acceptors and electron sources
During what phase of glycolysis is NADH formed? Please choose the correct answer from the following choices, and then select the submit answer button. during phase 3, when pyruvate is finally formed during phase 2, when glyceraldehyde 3-phosphate is formed during phase 3, when glyceraldehyde 3-phosphate is phosphorylated during phase 1, when glucose is phosphorylated during phase 1, when fructose 1,6-biphosphate is formed
Correct: during phase 3, when glyceraldehyde 3-phosphate is phosphorylated
In the first three stages of cellular respiration, the chemical energy in glucose is transferred to: cytochrome b and coenzyme Q. electron carriers and ATP. only coenzyme Q. proton pumps and ATP. ATP and cytochrome b.
Correct: electron carriers and ATP.
Cyclic electron transport enhances ATP production because: Please choose the correct answer from the following choices, and then select the submit answer button. proton translocation decreases. electrons are transferred from ferredoxin to plastoquinone. ADP production increases. photosystem I pumps more protons. cyclic electron transport is more energy efficient than linear electron
Correct: electrons are transferred from ferredoxin to plastoquinone.
The first phase of glycolysis requires the input of two ATP molecules. It is therefore: reducing. endergonic. oxidative. exergonic.
Correct: endergonic.
Antennae accompany reaction centers, promoting _____. Please choose the correct answer from the following choices, and then select the submit answer button. electron transfer H+ transfer energy transfer heat loss fluorescence
Correct: energy transfer
Pyruvate oxidation is remarkably similar to glycolysis in that when one molecule of pyruvate enters into a mitochondrion, two molecules of acetyl-CoA are formed. Please choose the correct answer from the following choices, and then select the submit answer button. true false
Correct: false
Where does the oxygen come from that is produced as a by-product of photosynthesis? from the Calvin cycle from the reduction of CO2 from breakdown of water from the breakdown of carbohydrates
Correct: from breakdown of water
In cellular respiration, oxygen: gains electrons and is an oxidizing agent. loses electrons and is a reducing agent. gains electrons and is a reducing agent. loses electrons and is an oxidizing agent.
Correct: gains electrons and is an oxidizing agent.
Proteins can be broken down for energy. They are typically broken down into amino acids, which then enter cellular respiration by: Please choose the correct answer from the following choices, and then select the submit answer button. - glycolysis or ethanol fermentation. lactic acid fermentation or the citric acid cycle. glycolysis or the citric acid cycle. electron transport/oxidative phosphorylation.
Correct: glycolysis or the citric acid cycle.
Fermentation takes place: on the outer mitochondrial membrane. in the cytoplasm. in the intermembrane space of mitochondria. on the inner mitochondrial membrane. in the mitochondrial matrix.
Correct: in the cytoplasm.
During pyruvate oxidation, pyruvate is broken down into CO2 and an acetyl group. The CO2 is: less oxidized than the acetyl group. more reduced than the acetyl group. more energetic than the acetyl group. less energetic than the acetyl group.
Correct: less energetic than the acetyl group.
ATP production in photosynthesis requires: Please choose the correct answer from the following choices, and then select the submit answer button. light. electrons. light and protons. light, electrons, and protons. protons
Correct: light, electrons, and protons.
Reactive oxygen species are detoxified in order to: Please choose the correct answer from the following choices, and then select the submit answer button. recover electrons. enhance linear electron transport. enhance cyclic electron transport. minimize damage to membranes. All of these choices are correct.
Correct: minimize damage to membranes.
Which of the following is not an end product for an acetyl group that enters the citric acid cycle? CO2 ATP FADH2 NADH oxaloacetate
Correct: oxaloacetate
During the citric acid cycle, the production of CO2 is the result of the _____ of intermediate compounds of the citric acid cycle coupled to the production of _____. Please choose the correct answer from the following choices, and then select the submit answer button. reduction; ATP oxidation; ATP reduction; NADH oxidation; NADH oxidation; GTP
Correct: oxidation; NADH
Which of the following does not occur during the third phase of glycolysis? Please choose the correct answer from the following choices, and then select the submit answer button. ATP synthesis the transfer of high-energy electrons to NAD+ oxygen consumption pyruvate production
Correct: oxygen consumption
In the second phase of glycolysis: phosphate groups are added to glucose. phosphorylated sugar molecule is cleaved and the products rearranged. ATP is generated by substrate-level phosphorylation. NAD+ is reduced to NADH. ATP is generated by oxidative phosphorylation.
Correct: phosphorylated sugar molecule is cleaved and the products rearranged.
The occurrence of photorespiration _____ CO2 and _____ ATP. produces; consumes reduces; produces oxidizes; produces produces; produces consumes; consumes
Correct: produces; consumes
Which stage of cellular respiration occurs immediately after pyruvate is produced? glycolysis pyruvate oxidation citric acid cycle electron transport oxidative phosphorylation
Correct: pyruvate oxidation
The _____ forms of the electron carriers NAD+/NADH and FADH/FADH2 have high potential energy. Please choose the correct answer from the following choices, and then select the submit answer button. oxidized reduced phosphorylated carboxylated
Correct: reduced
During fermentation, pyruvate is: Please choose the correct answer from the following choices, and then select the submit answer button. oxidized. reduced. phosphorylated. carboxylated. hydrogenated.
Correct: reduced.
Which step of the Calvin cycle would be affected first by a lack of NADPH? reduction carboxylation regeneration All of these choices are correct.
Correct: reduction
Fermentation occurs in: only in bacteria and plants. anaerobic organisms only. some aerobic organisms, such as yeast, even in the presence of oxygen.
Correct: some aerobic organisms, such as yeast, even in the presence of oxygen.
Gibbs free energy is defined as: the amount of potential energy in a system. the amount of energy available to do work. the amount of energy lost as heat. the amount of entropy. spontaneous energy.
Correct: the amount of energy available to do work.
The Z scheme refers to: the changes in the energy level of electron donors during the photosynthetic electron transport chain. the path of electrons between photosystem II and cytochrome b6f. electron transport. the use of H2O as an electron source. proton translocation.
Correct: the changes in the energy level of electron donors during the photosynthetic electron transport chain.
Which is the only reaction in the citric acid cycle that produces ATP by substrate-level phosphorylation? the formation of fumarate the formation of citrate the formation of malate the formation of succinate the formation of oxaloacetate
Correct: the formation of succinate
Coenzyme Q and cytochrome c: transfer electrons between protein complexes of the electron transport chain. transfer high-energy electrons from NADH and FADH2 to protein complexes of the electron transport chain. transfer electrons to ATP synthase. transfer electrons to oxygen at the end of the electron transport chain.
Correct: transfer electrons between protein complexes of the electron transport chain.
At the end of glycolysis, the carbon molecules originally found in the starting glucose molecule are in the form of: Please choose the correct answer from the following choices, and then select the submit answer button. . two pyruvate molecules. two ATP molecules. one pyruvate molecule. two NADH molecules. four ATP molecules.
Correct: two pyruvate molecules
Photosystem I is a _____ than photosystem II. Please choose the correct answer from the following choices, and then select the submit answer button. weaker oxidant stronger oxidant stronger reductant weaker oxidant and a stronger reductant stronger oxidant and a stronger reductant
Correct: weaker oxidant and a stronger reductant
The reaction of iron with oxygen to form iron oxide is an example of an oxidation-reduction reaction: 4Fe + 3O2 → 2Fe2O3. In this reaction ______loses electrons and is _____
Fe; oxidized
During their experiments with chlorella, Calvin and Benson found no free glucose. Why do you think this is? a. Glucose would cause H2O to leave the Chlorella cells b. Glucose is stored as starch c. Glucose is an isomer of fructose d. Green algae do not respire when illuminated. e. Glucose takes too long to synthesize.
Glucose is stored as starch
Which of the following best describes how ATP synthase converts the potential energy of the proton gradient to the chemical energy of ATP? Do protons flow through the Fo or F1? - Kinetic energy from the flow of protons is converted to the kinetic energy of rotation of the Fo subunit; the rotation of the Fo subunit leads to rotation of the F1 subunit, which can then catalyze ATP synthesis. - The flow of protons through the F0 subunit reduces the F1 subunit, which allows ADP to be oxidized to ATP. - The flow of protons through the F0 subunit oxidizes the F1 subunit, which allows ADP to be reduced to ATP.. - Kinetic energy from the flow of protons is stored in a new electrochemical gradient within the F0 subunit. The potential energy of the electrochemical gradient, in turn, is converted to kinetic energy in the F1 subunit and used to catalyze ATP synthesis.
Kinetic energy from the flow of protons is converted to the kinetic energy of rotation of the Fo subunit; the rotation of the Fo subunit leads to rotation of the F1 subunit, which can then catalyze ATP synthesis.
The reaction of iron with oxygen to form iron oxide is an example of an oxidation-reduction reaction: 4Fe + 3O2 → 2Fe2O3. In this reaction ______ gains electrons and is _________
O2; reduced
Which one of the following statements BEST represents the relationship between cellular respiration and photosynthesis? Photosynthesis occurs only during the day and respiration occurs only at night. Photosynthesis stores energy in organic molecules, while respiration releases it. Respiration stores energy in organic molecules, while photosynthesis releases it. Respiration occurs only in animals and photosynthesis occurs only in plants. Photosynthesis reverses the biochemical pathways of respiration
Respiration stores energy in organic molecules, while photosynthesis releases it.
Why does rubisco have such a low catalytic rate (that is, why is it so slow)?
Rubisco faces a fundamental trade-off between selectivity and speed because it can use both CO2 and O2 as substrates. High selectivity of CO2 over O2 requires that the reaction have a high energy barrier, leading to a lower catalytic rate.
Which of the following correctly describes the role of rubisco in the Calvin cycle? Rubisco incorporates CO2 from the atmosphere into an organic molecule. Rubisco uses NADPH to reduce 3-phosphoglycerate to a three carbon sugar. None of the other answer options is correct. Rubisco uses ATP to regenerate RUBP.
Rubisco incorporates CO2 from the atmosphere into an organic molecule.
Which of the following statements is true regarding the equation C6H12O6 + 6O2 →6CO2+ 6H2O + energy? Please choose the correct answer from the following choices, and then select the submit answer button. The movement of hydrogen atoms in reactions involving C6H12O6 and H2O yields no information regarding the movement of electrons. Glucose could be considered a reducing agent. In the production of CO2 from glucose, the oxygen atoms lose electrons and the carbon atom is oxidized. The oxygen atoms in both CO2 and H2O are electronegative. The oxygen atoms in both CO2 and H2O are electronegative, and glucose is considered a reducing agent.
The oxygen atoms in both CO2 and H2O are electronegative, and glucose is considered a reducing agent.
Which of the following statements must be true in order for mitochondrial ATP synthase to function properly The pH of the intermembrane space must be higher than the pH of the mitochondrial matrix. There must be no difference in pH between the mitochondrial matrix and the intermembrane space. The pH of the intermembrane space must be lower than the pH of the mitochondrial matrix
The pH of the intermembrane space must be lower than the pH of the mitochondrial matrix
For each of the following pairs of molecules, indicate which member of the pair is reduced and which is oxidized, and which has more chemical energy and which has less chemical energy: NAD+/NADH; FAD/FADH2; CO2/C6H12O6.
The reduced molecules are NADH, FADH2, and C6H12O6, and the oxidized molecules are NAD+, FAD, and CO2. The reduced forms have more chemical energy than their corresponding oxidized forms
Which of the following best describes the benefit to early photosynthetic organisms gained by having two different photosystems in one cell? They could use water as an electron donor They produced oxygen. They could thrive in places where there was little or almost no light. These organisms produced carbohydrates at twice the rate of organisms with a single photosystem.
They could use water as an electron donor
In human cells such as muscle tissue, the product of fermentation is
acetic acid. pyruvate. ethanol. FADH2. lactic acid.
In which form are electrons transferred during typical redox reactions such as the oxidation of glucose? as oxygen atoms as phosphate groups as hydrogen atoms as carbon atoms as free electrons
as hydrogen atoms
Which one of the following is NOT a product when photosystem II oxidizes a molecule of water? carbon dioxide oxygen protons electrons
carbon dioxide
Imagine that you discover a carnivorous deep-sea fish that cannot utilize the carbon in carbonic acid (or any other inorganic molecule) present in seawater to form glucose (or other organic molecules). Living so far beneath the water's surface, this fish is also incapable of harnessing energy from the sun. This fish would be considered a: photoautotroph. phototroph. chemoautotroph. chemoheterotroph. photoheterotroph.
chemoheterotroph.
Which one of the following does NOT actively move protons from the mitochondrial matrix to the intermembrane space? complex I complex IV None of the other answer options is correct. complex III complex II
complex II
Which of the following is responsible for the transport of electrons between photosystem II and photosystem I? Please choose the correct answer from the following choices, and then select the submit answer button. water. cytochrome b6f. NADP+. chlorophyll. NADPH.
cytochrome b6f.
The phosphorylation of glucose during glycolysis serves to: (Select all that apply.) destabilize the molecule, making it easier to cleave. reduce an electron carrier, storing energy for later. trap imported glucose inside the cell.
destabilize the molecule, making it easier to cleave. trap imported glucose inside the cell.
In the Calvin cycle, ATP is required to: carboxylate RuBP. donate a phosphate group to 3-PGA. reduce 3-PGA. reduce triose phosphates.. reduce RuBP.
donate a phosphate group to 3-PGA
PFK-1 is _____ by ATP and _____ by ADP. inhibited; inhibited activated; activated activated; inhibited inhibited; activated
inhibited; activated
The chemical bonds of carbohydrates and lipids have high potential energy because: many of these bonds are C—C and C—H bonds. they are strong oxidizing agents. they are easy to phosphorylate. they are easy to hydrolyze. they are strong reducing agents.
many of these bonds are C—C and C—H bonds.
The energy in organic molecules is released in a series of steps because: more total energy is released in multiple steps than would be released in a single step. more energy can be harvested for cellular use in multiple steps than from a single step. less total energy is released in multiple steps than would be released in a single step. only a single electron can be moved at a time in a cellular reaction. it is not possible to release it in a single step.
more energy can be harvested for cellular use in multiple steps than from a single step
he citric acid cycle begins when acetyl-CoA combines with _____ to form _____. oxaloacetate; citrate malate; oxaloacetate oxaloacetate; malate pyruvate; citrate citrate; cis-aconitate
oxaloacetate; citrate
Photorespiration occurs because: rubisco is a selective catalyst. rubisco is a slow catalyst. there is more O2 than CO2 in the atmosphere. there is more O2 than CO2 and rubisco is a selective catalyst.
there is more O2 than CO2 in the atmosphere.
