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Chapter Chapter 6: How Cells Harvest Chemical Energy
 
Chapter Quiz
 

1 .       Humans exchange oxygen and carbon dioxide with the atmosphere via their _____. (6.2) [Hint]

 kidneys
 liver
 pancreas
 lungs
 skin
2 .       In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and in a few minutes radioactive oxygen atoms showed up in _____. (6.3) [Hint]

 carbon dioxide
 NADH
 water
 ATP
 oxygen gas
3 .       The function of cellular respiration is to _____. (6.3) [Hint]

 reduce CO2
 extract CO2 from the atmosphere
 extract usable energy from glucose
 synthesize macromolecules from monomers
 produce carbohydrates
4 .       An electron carrier acts as an energy-storage molecule when it is __________ (for example, __________). (6.5) [Hint]

 reduced ... NAD
 oxidized ... NAD
 oxidized ... NADH
 reduced ... NADH
 oxidized ... FADH2
5 .       The principal hydrogen-atom-carrier molecules in cells are composed of ___________. (6.5) [Hint]

 amino acids
 fatty acids
 nucleotides
 sugars
 phospholipids
6 .       A molecule is oxidized when it _____. (6.5) [Hint]

 changes shape
 gains a hydrogen (H+) ion
 loses a hydrogen (H+) ion
 gains an electron
 loses an electron
7 .       Which one of the following best describes the electron transport chain? (6.5) [Hint]

 Electrons are pumped across a membrane by active transport.
 Acetyl CoA is fully oxidized to CO2.
 Hydrogens are added to CO2 to make an energy-rich compound.
 Electrons pass from one carrier to another, releasing a little energy at each step.
 Glucose is broken down to a three-carbon compound in preparation for the Citric Acid Cycle.
8 .       During respiration in a eukaryotic cell, reactions of glycolysis occur ___________. (6.7) [Hint]

 in the cytoplasmic fluid
 in the mitochondria
 on the inner mitochondrial membrane
 within the intermembrane space of the mitochondrion
 across the inner membrane of the mitochondrion
9 .       A small amount of ATP is made in glycolysis _____. (6.7) [Hint]

 by the transfer of a phosphate group from a fragment of glucose to ADP (substrate-level phosphorylation)
 using energy from the sun to perform photosynthesis
 by the transport of electrons through a series of carriers
 when electrons and hydrogen atoms are transferred to NAD+
 as a product of chemiosmosis
10 .       A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to kill bacteria in people with infections. But he can't do this because _____. (6.7) [Hint]

 bacteria are facultative anaerobes; they usually don't need to perform glycolysis
 glycolysis produces so little ATP that the drug will have little effect
 human cells also perform glycolysis; the drug might also poison them
 bacteria do not perform glycolysis
 glycolysis can occur without the action of enzymes
11 .       What is the name of the process in which glucose is converted to pyruvic acid? (6.7) [Hint]

 chemiosmotic theory
 fermentation
 glycolysis
 the Citric Acid Cycle
 none of the above
12 .       In preparing pyruvic acid to enter the Citric Acid Cycle, which of the following steps does NOT occur? (6.8) [Hint]

 Pyruvic acid is oxidized by reducing an NAD+ to an NADH.
 A carbon atom is released in carbon dioxide.
 A compound called coenzyme A binds to a two-carbon fragment.
 Oxygen must be present for the pyruvic acid to enter the Citric Acid Cycle.
 The two-carbon fragment formed after a carbon atom is released as carbon dioxide is called lactic acid.
13 .       When pyruvic acid is converted to acetyl CoA ___________. (6.8) [Hint]

 CO2 and ATP are formed
 CO2 and NADH are formed
 CO2 and coenzyme A are formed
 one turn of the Citric Acid Cycle is completed
 NAD is regenerated
14 .       During respiration in a eukaryotic cell, reactions of the Citric Acid Cycle occur in ___________. (6.9) [Hint]

 the cytoplasmic fluid
 the mitochondrion
 the folds of the inner mitochondrial membrane
 the intermembrane space of the mitochondrion
 across the inner membrane of the mitochondrion
15 .       Of the metabolic pathways listed below, the only pathway found in almost all organisms is _____. (6.9) [Hint]

 cellular respiration
 the Citric Acid Cycle
 the electron transport chain
 glycolysis
 fermentation
16 .       Most of the high-energy electrons released from glucose by cell respiration _____. (6.9) [Hint]

 are used for synthesizing lactic acid
 are used to form ATP by the Citric Acid Cycle
 are bound to FAD to be sent through electron transport
 are in the carbon dioxide
 none of the above
17 .       Most of the NADH that delivers high-energy electrons to the electron transport chain comes from _____. (6.9) [Hint]

 chemiosmosis
 the cytoplasm
 glycolysis
 biosynthesis
 the Citric Acid Cycle
18 .       Why is the Citric Acid Cycle called a cycle? (6.9) [Hint]

 Glucose is cycled around and resynthesized.
 NAD+ and FAD are recycled.
 The two-carbon acetyl CoA binds to a four-carbon molecule that is restored at the end of the cycle to be used again in the Citric Acid Cycle.
 Carbon dioxide is cycled back to photosynthesis.
 NADH is cycled down the electron transport chain.
19 .       In the Citric Acid Cycle, the energy production per glucose molecule is _____. (6.9) [Hint]

 2 ATP, 6 NADH, 2 FADH2
 38 ATP
 4 ATP, 8 NADH
 2 ATP, 6 NADH
 1 ATP, 3 NADH, 1 FADH2
20 .       The major (but not sole) energy accomplishment of the Citric Acid Cycle is the ___________. (6.9) [Hint]

 formation of CO2
 formation of ATP
 formation of NADH and FADH2
 utilization of O2
 completion of substrate-level phosphorylations
21 .       Immediately after completion of the Citric Acid Cycle, most of the usable energy from the original glucose molecule is in the form of ___________. (6.9) [Hint]

 acetyl CoA
 ATP
 NADH
 CO2
 oxaloacetic acid
22 .       Which one of the following serves primarily as a hydrogen-atom-carrier molecule in cells? (6.9) [Hint]

 ATP
 CO2
 FAD
 RNA
 DNA
23 .       The energy given up by electrons as they move through the electron transport chain is used to _____. (6.10) [Hint]

 break down glucose
 make NADH and FADH2
 pump H+ through a membrane
 oxidize water
 manufacture glucose
24 .       The ATP synthase in a human cell gets energy for making ATP directly from _____. (6.10) [Hint]

 sunlight
 the flow of H+ through a membrane
 the oxidation of glucose
 the movement of electrons through a series of carriers
 the reduction of oxygen
25 .       The enzyme ATP synthase forms ATP _____. (6.10) [Hint]

 due to the potential energy of a concentration gradient of hydrogen ions across a membrane
 due to substrate-level phosphorylation
 from glucose in the absence of oxygen
 in the absence of chemiosmosis
 from GTP
26 .       In respiration, which one of the following is NOT done directly by the electron transport chain (or its components)? (6.10) [Hint]

 carry electrons
 carry protons
 phosphorylate ADP to make ATP
 regenerate (oxidized) FAD
 form a proton gradient
27 .       During chemiosmosis in eukaryotic cells, ATP synthase catalyzes the phosphorylation of ADP to form ATP. The energy needed for this endergonic reaction comes from _____. (6.10) [Hint]

 DNA replication
 the movement of hydrogen ions from the intermembrane space to the mitochondrial matrix
 the fermentation of pyruvic acid to form lactic acid
 the movement of FADH from the cytoplasm to the mitochondria
 the reduction of NAD+ to form NADH
28 .       Which one of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria? (6.10) [Hint]

 ATP
 ATP pump
 cytochrome c
 electron transport chain
 electrons
29 .       During respiration in a eukaryotic cell, the electron transport chain is located in or on the ___________. (6.10) [Hint]

 cytoplasmic fluid
 the mitochondrion
 cristae of the mitochondrion
 intermembrane space of the mitochondrion
 none of the above
30 .       Most of the ATP produced in cellular respiration comes from _____. (6.10) [Hint]

 glycolysis
 chemiosmosis
 lactic acid fermentation
 biosynthesis
 the Citric Acid Cycle
31 .       Which of the following substances, if any, is NOT involved in chemiosmosis? (6.10) [Hint]

 ADP
 oxygen
 ATP
 ATP synthase
 All of the above are involved in chemiosmosis.
32 .       When a poison such as rotenone blocks the electron transport chain, glycolysis and the Citric Acid Cycle soon grind to a halt as well, because _____. (6.11) [Hint]

 they run out of ATP
 the buildup of unused oxygen interferes with glycolysis and the Citric Acid Cycle
 they run out of NAD+ and FAD
 electrons are no longer available from the electron transport chain
 they run out of ADP
33 .       Which part of the cellular catabolism of glucose requires molecular oxygen (O2)? (6.12) [Hint]

 glycolysis
 the Citric Acid Cycle
 the electron transport chain
 fermentation
 all of the above
34 .       During aerobic respiration, molecular oxygen (O2) is used _____. (6.12) [Hint]

 at the end of glycolysis to switch from the fermentation pathway
 at the end of the Citric Acid Cycle to cycle back to citric acid
 between glycolysis and the Citric Acid Cycle to split a carbon from pyruvic acid
 between the Citric Acid Cycle and the electron transport chain to move NADH and FADH2
 at the end of electron transport chain to accept electrons and form H2O
35 .       If humans did not breathe in O2, we would not _____. (6.12) [Hint]

 make enough ATP to meet our energy requirements
 have enough enzymes to catalyze reactions
 be able to perform lactic acid fermentation
 be able to synthesize organic molecules from inorganic molecules
 be affected because we can switch to alcoholic fermentation
36 .       During the reaction C6H12O6 + 6 O2 —> 6 CO2 + 6 H2O, ___________. (6.12) [Hint]

 oxygen becomes reduced
 glucose becomes reduced
 CO2 becomes reduced
 water becomes reduced
 both glucose and CO2 become reduced
37 .       Each ATP molecule contains about 1% of the amount of chemical energy in a single glucose molecule. Cell respiration produces about 38 ATP from one glucose. What happens to the rest of the energy in the glucose? (6.12) [Hint]

 It is stored as fat.
 It is converted to heat.
 It is used to make water from hydrogen ions and oxygen.
 It is used directly for energy.
 It is stored as starch.
38 .       The overall efficiency of respiration is approximately _____. (6.12) [Hint]

 0.50%
 2%
 40%
 94%
 100%
39 .       In cellular respiration, _____ is oxidized and _____ is reduced. (6.12) [Hint]

 oxygen ... ATP
 ATP ... oxygen
 glucose ... oxygen
 carbon dioxide ... water
 glucose ... ATP
40 .       How many ATPs are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen? (6.12) [Hint]

 2 ATP
 4 ATP
 6 ATP
 36 ATP
 none of the above
41 .       Fermentation is essentially glycolysis plus an extra step in which pyruvic acid is reduced to form lactic acid or alcohol and carbon dioxide. This last step _____. (6.13) [Hint]

 removes poisonous oxygen from the environment
 extracts a bit more energy from glucose
 enables the cell to recycle NAD+
 inactivates toxic pyruvic acid
 enables the cell to make pyruvic acid into substances it can use
42 .       Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of _____. (6.13) [Hint]

 ATP
 lactic acid
 carbon dioxide
 ADP
 oxygen
43 .       How much ATP can a cell make from one glucose molecule in the presence of carbon monoxide? (6.13) [Hint]

 none
 2 ATP
 4 ATP
 38 ATP
 18 ATP
44 .       In glycolysis in the absence of oxygen, cells need a way to regenerate which compound? (6.13) [Hint]

 ethanol
 carbon dioxide
 NAD+
 lactic acid
 glucose
45 .       Muscle tissues make lactic acid from pyruvic acid in order to _____. (6.13) [Hint]

 enable you to get drunk
 get rid of toxic pyruvic acid
 utilize the energy in pyruvic acid
 utilize the released CO2
 regenerate (oxidized) NAD+
46 .       When protein molecules are used as fuel for cellular respiration, _____ are produced as waste. (6.14) [Hint]

 amino groups
 fatty acids
 sugar molecules
 molecules of lactic acid
 ethanol and CO2
47 .       A gram of fat oxidized by respiration produces approximately _____ as much ATP as a gram of carbohydrate. (6.14) [Hint]

 half
 twice
 4 times
 10 times
 100 times
48 .       Which intermediate in the oxidation of glucose can be used in the synthesis of fats? (6.15) [Hint]

 amino acids
 maltose
 acetyl CoA
 amino acids and maltose
 fatty acids