AP Biology Chapter 9 Review

Multiple Choice
Identify the choice that best completes the statement or answers the question.

____	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	

____	2.	The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction
a.	gains electrons and gains energy.	
b.	loses electrons and loses energy.	
c.	gains electrons and loses energy.	
d.	loses electrons and gains energy.	
e.	neither gains nor loses electrons, but gains or loses energy.	

____	3.	Why does the oxidation of organic compounds by molecular oxygen to produce  and water release free energy?
a.	The covalent bonds in organic molecules are higher energy bonds than those 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  than they do in organic compounds.	
e.	The covalent bond in  is unstable and easily broken by electrons from organic molecules.	

____	4.	Which of the following statements describes the results of this reaction?

a.	 is oxidized and  is reduced.	
b.	 is oxidized and  is reduced.	
c.	 is reduced and  is oxidized.	
d.	 is reduced and  is oxidized.	
e.	 is reduced and  is oxidized.	

____	5.	When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes
a.	dehydrogenated.	
b.	hydrogenated.	
c.	oxidized.	
d.	reduced.	
e.	an oxidizing agent.	

____	6.	When a molecule of NAD (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a hydrogen ion) the molecule becomes
a.	hydrogenated.	
b.	oxidized.	
c.	reduced.	
d.	redoxed.	
e.	a reducing agent.	

____	7.	Which of the following statements describes NAD?
a.	NAD is reduced to NADH during both glycolysis and the citric acid cycle.	
b.	NAD has more chemical energy than NADH.	
c.	NAD is reduced 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.	

____	8.	Where does glycolysis takes place?
a.	mitochondrial matrix	
b.	mitochondrial outer membrane	
c.	mitochondrial inner membrane	
d.	mitochondrial intermembrane space	
e.	cytosol	

____	9.	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	

____	10.	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	

____	11.	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.	attaches itself to NAD.	

____	12.	Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed during glycolysis?
a.	0%	
b.	2%	
c.	10%	
d.	38%	
e.	100%	

____	13.	During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is
a.	transferred to ADP, forming ATP.	
b.	transferred directly to ATP.	
c.	retained in the pyruvate.	
d.	stored in the NADH produced.	
e.	used to phosphorylate fructose to form fructose-6-phosphate.	

____	14.	In addition to ATP, what are the end products of glycolysis?
a.	 and 	
b.	 and pyruvate	
c.	NADH and pyruvate	
d.	 and NADH	
e.	, , and citrate	

____	15.	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	

____	16.	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.	

Use the following information to answer the next questions.

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate 1) loses a carbon, which is given off as a molecule of , 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A.

____	17.	Why is coenzyme A, a sulfur containing molecule derived from a B vitamin, added?
a.	because sulfur is needed for the molecule to enter the mitochondrion	
b.	in order to utilize this portion of a B vitamin which would otherwise be a waste product from another pathway	
c.	to provide a relatively unstable molecule whose acetyl portion can readily bind to oxaloacetate	
d.	because it drives the reaction that regenerates NAD	
e.	in order to remove one molecule of 	

____	18.	How does pyruvate enter the mitochondrion?
a.	active transport	
b.	diffusion	
c.	facilitated diffusion	
d.	through a channel	
e.	through a pore	

____	19.	Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon () from one molecule of pyruvate?
a.	lactate	
b.	glyceraldehydes-3-phosphate	
c.	oxaloacetate	
d.	acetyl CoA	
e.	citrate	

____	20.	How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?
a.	2	
b.	4	
c.	6	
d.	8	
e.	10	

Refer to Figure 9.2, showing the citric acid cycle, as a guide to answer the following questions.

Figure 9.2

____	21.	Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through substrate-level phosphorylation?
a.	1	
b.	2	
c.	11	
d.	12	
e.	24	

____	22.	How many reduced dinucleotides would be produced with four turns of the citric acid cycle?
a.	1  and 4 NADH	
b.	2  and 8 NADH	
c.	4  and 12 NADH	
d.	1 FAD and 4 NAD	
e.	4 FAD and 12 NAD	

____	23.	Starting with citrate, which of the following combinations of products would result from three turns of the citric acid cycle?
a.	1 ATP, 2 , 3 NADH, and 1 	
b.	2 ATP, 2 , 1 NADH, and 3 	
c.	3 ATP, 3 , 3 NADH, and 3 	
d.	3 ATP, 6 , 9 NADH, and 3 	
e.	38 ATP, 6 , 3 NADH, and 12 	

____	24.	Carbon dioxide () 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	

____	25.	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.	

____	26.	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	

____	27.	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	

____	28.	Which of the following describes the sequence of electron carriers in the electron transport chain, starting with the least electronegative?
a.	ubiquinone (Q), cytochromes (Cyt), FMN, Fe•S	
b.	cytochromes (Cyt), FMN, ubiquinone, Fe•S	
c.	Fe•S, FMN, cytochromes (Cyt), ubiquinone	
d.	FMN, Fe•S, ubiquinone, cytochromes (Cyt)	
e.	cytochromes (Cyt), Fe•S, ubiquinone, FMN	

____	29.	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 + 	
e.		

____	30.	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 .	
d.	combine with lactate, forming pyruvate.	
e.	catalyze the reactions of glycolysis.	

____	31.	In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP +  to ATP?
a.	energy released as electrons flow through the electron transport system	
b.	energy released from substrate-level phosphorylation	
c.	energy released from ATP synthase pumping hydrogen ions from the mitochondrial matrix	
d.	energy released from movement of protons through ATP synthase	
e.	No external source of energy is required because the reaction is exergonic.	

____	32.	The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation is
a.	oxidation of glucose to  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 difference in H concentrations on opposite sides of the inner mitochondrial membrane.	
e.	the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.	

____	33.	It is possible to prepare vesicles from portions of the inner membrane of the mitochondrial components. 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	

____	34.	Each time a molecule of glucose () is completely oxidized via aerobic respiration, how many oxygen molecules () are required?
a.	1	
b.	2	
c.	6	
d.	12	
e.	38	

____	35.	Which of the following produces the most ATP when glucose () is completely oxidized to carbon dioxide () and water?
a.	glycolysis	
b.	fermentation	
c.	oxidation of pyruvate to acetyl CoA	
d.	citric acid cycle	
e.	oxidative phosphorylation (chemiosmosis)	

____	36.	Assume a mitochondrion contains 58 NADH and 19 . If each of the 77 dinucleotides were used, approximately how many ATP molecules could be generated as a result of oxidative phosphorylation (chemiosmosis)?
a.	36	
b.	77	
c.	173	
d.	212	
e.	1102	

____	37.	Recall that the complete oxidation of a mole of glucose releases 686 kcal of energy (ΔG = -686 kcal/mol). The phosphorylation of ADP to form ATP stores approximately 7.3 kcal per mole of ATP. What is the approximate efficiency of cellular respiration for a "mutant" organism that produces only 29 moles of ATP for every mole of glucose oxidized, rather than the usual 36-38 moles of ATP?
a.	0.4%	
b.	25%	
c.	30%	
d.	40%	
e.	60%	

____	38.	What is proton-motive force?
a.	the force required to remove an electron from hydrogen	
b.	the transmembrane proton concentration gradient	
c.	movement of hydrogen into the intermembrane space	
d.	movement of hydrogen into the mitochondrion	
e.	the addition of hydrogen to NAD	

____	39.	In liver cells, the inner mitochondrial membranes are about 5 X the area of the outer mitochondrial membranes, and about 17 X that of the cell's plasma membrane. What purpose must this serve?
a.	It allows for increased rate of glycolysis.	
b.	It allows for increased rate of the citric acid cycle.	
c.	It increases the surface for oxidative phosphoryation.	
d.	It increases the surface for substrate-level phosphorylation.	
e.	It allows the liver cell to have fewer mitochondria.	

Use the following to answer the following questions.

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. If the membranes are agitated still further however, the ability to synthesize ATP is lost.

____	40.	After the second agitation of the membrane vesicles, what must be lost from the membrane?
a.	the ability of NADH to transfer electrons to the first acceptor in the electron transport chain	
b.	the prosthetic groups like heme from the transport system	
c.	cytochromes	
d.	ATP synthase, in whole or in part	
e.	the contact required between inner and outer membrane surfaces	

____	41.	It should be possible to reconstitute the abilities of the vesicles if which of the following is added?
a.	cytochromes	
b.	extra NADH	
c.	a second membrane surface	
d.	more electrons	
e.	intact ATP synthase	

Figure 9.3

____	42.	The accompanying figure shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain?
a.	oxygen, carbon dioxide, and water	
b.	NAD, FAD, and electrons	
c.	NADH, , and protons	
d.	NADH, , and electrons	
e.	Oxygen and electrons	

____	43.	Which of the following most accurately describes what is happening along this chain?
a.	Chemiosmosis is coupled with electron transfer.	
b.	Each electron carrier alternates between being reduced and being oxidized.	
c.	ATP is generated at each step.	
d.	Energy of the electrons increases at each step.	
e.	Molecules in the chain give up some of their potential energy.	

____	44.	The parts of the figure labeled with Roman numerals symbolize what concept?
a.	different inner mitochondrial membranes	
b.	different mitochondria functioning together	
c.	molecules with different attached metal ions	
d.	carbohydrate framework holding the molecules in place	
e.	multimeric groups of proteins in 4 complexes	

____	45.	What happens at the end of the chain?
a.	The 2 original electrons combine with NAD.	
b.	The 2 original electrons combine with oxygen.	
c.	4 electrons combine with oxygen and protons.	
d.	4 electrons combine with hydrogen and oxygen atoms.	
e.	1 electron combines with oxygen and hydrogen.	

____	46.	Which of the following describes ubiquinone?
a.	a protein in the electron transport chain	
b.	a small hydrophobic coenzyme	
c.	a substrate for synthesis of FADH	
d.	a vitamin needed for efficient glycolysis	
e.	an essential amino acid	

____	47.	Which of the following normally occurs whether or not oxygen () is present?
a.	glycolysis	
b.	fermentation	
c.	oxidation of pyruvate to acetyl CoA	
d.	citric acid cycle	
e.	oxidative phosphorylation (chemiosmosis)	

____	48.	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	

____	49.	In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
a.	ATP, , and ethanol (ethyl alcohol).	
b.	ATP, , and lactate.	
c.	ATP, NADH, and pyruvate.	
d.	ATP, pyruvate, and oxygen.	
e.	ATP, pyruvate, and acetyl CoA.	

____	50.	In alcohol fermentation, NAD is regenerated from NADH during which of the following?
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 NAD in the citric acid cycle	
e.	phosphorylation of ADP to form ATP	

____	51.	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 is found in the cytosol, does not involve 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.	

____	52.	Muscle cells, when an individual is exercising heavily and when the muscle becomes oxygen deprived, convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells?
a.	It is converted to NAD.	
b.	It produces  and water.	
c.	It is taken to the liver and converted back to pyruvate.	
d.	It reduces  to FAD.	
e.	It is converted to alcohol.	

____	53.	When muscle cells are oxygen deprived, the heart still pumps. What must the heart 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	

____	54.	When 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.	

____	55.	You have a friend who lost 7 kg (about 15 pounds) of fat on a "low carb" diet. How did the fat leave her body?
a.	It was released as  and .	
b.	Chemical energy 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.	

____	56.	Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements describes a function of phosphofructokinase?
a.	It is activated by AMP (derived from ADP).	
b.	It is activated by ATP.	
c.	It is inhibited 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.	

____	57.	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 non-photosynthesizing cells only	
c.	in cells that are storing glucose only	
d.	in photosynthesizing cells in dark periods and in other tissues all the time	
e.	in photosynthesizing cells in the light and in other tissues in the dark	

____	58.	In vertebrate animals, brown fat tissue's color is due to abundant mitochondria. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few mitochondria. 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 synthase	
d.	to allow other membranes of the cell to perform mitochondrial function	
e.	to regulate temperature by converting energy from NADH oxidation to heat	

____	59.	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	

____	60.	What is the reducing agent in the following reaction?
Pyruvate + NADH + H ® Lactate + NAD
a.	oxygen	
b.	NADH	
c.	NAD	
d.	lactate	
e.	pyruvate	

____	61.	The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is
a.	the oxidation of glucose and other organic compounds.	
b.	the flow of electrons down the electron transport chain.	
c.	the affinity of oxygen for electrons.	
d.	the H concentration gradient across the inner mitochondrial membrane.	
e.	the transfer of phosphate to ADP.	

____	62.	The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
a.	oxygen.	
b.	water.	
c.	NAD.	
d.	pyruvate.	
e.	ADP.	

____	63.	Cells do not catabolize carbon dioxide because
a.	its double bonds are too stable to be broken.	
b.	 has fewer bonding electrons than other organic compounds.	
c.	 is already completely reduced.	
d.	 is already completely oxidized.	
e.	the molecule has too few atoms.	

____	64.	Which of the following is a true distinction between fermentation and cellular respiration?
a.	Only respiration oxidizes glucose.	
b.	NADH is oxidized by the electron transport chain in respiration only.	
c.	Fermentation, but not respiration, is an example of a catabolic pathway.	
d.	Substrate-level phosphorylation is unique to fermentation.	
e.	NAD functions as an oxidizing agent only in respiration.	

____	65.	Most  from catabolism is released during
a.	glycolysis.	
b.	the citric acid cycle.	
c.	lactate fermentation.	
d.	electron transport.	
e.	oxidative phosphorylation.