Biology Chapter 13: How Cells Obtain Energy From Food (Multiple Choice Questions Sample)

CHAPTER 13
HOW CELLS OBTAIN ENERGY FROM FOOD
2009 Garland Science Publishing
The Breakdown and Utilization of Sugars and Fats
13-1Glycolysis is an anaerobic process used to catabolize glucose. What does it mean for this process to be anaerobic?
(a)No oxygen is required.
(b)No oxidation occurs.
(c)It takes place in the lysosome.
(d)Glucose is broken down by the addition of electrons.
13-2Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP?
(a)the digestion of starch to glucose
(b)glycolysis
(c)the citric acid cycle
(d)oxidative phosphorylation
13-3The advantage to the cell of the gradual oxidation of glucose during cellular respiration compared with its combustion to CO2 and H2O in a single step is that ________________.
(a)more free energy is released for a given amount of glucose oxidized
(b)no energy is lost as heat
(c)energy can be extracted in usable amounts
(d)more CO2 is produced for a given amount of glucose oxidized
13-4The final metabolite produced by glycolysis is ___________.
(a)acetyl CoA
(b)pyruvate
(c)3-phosphoglycerate
(d)glyceraldehyde 3-phosphate
13-5Glycolysis generates more stored energy than it expends. What is the net number of activated carrier molecules produced in this process (number and type of molecules produced minus the number of those molecules used as input)?
(a)6 ATP, 2 NADH
(b)4 ATP, 4 NADH
(c)2 ATP, 2 NADH
(d)4 ATP, 2 NADH
13-6Which of the following steps or processes in aerobic respiration include the production of carbon dioxide?
(a)breakdown of glycogen
(b)glycolysis
(c)conversion of pyruvate to acetyl CoA
(d)oxidative phosphorylation
13-7In step 4 of glycolysis, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to produce two three-carbon molecules (dihydroxyacetone phosphate and glyceraldehyde 3-phosphate). Which enzyme catalyzes this reaction?
(a)aldolase
(b)phosphoglucose isomerase
(c)enolase
(d)triose phosphate isomerase
13-8On a diet consisting of nothing but protein, which of the following is the most likely outcome?
(a)loss of weight because amino acids cannot be used for the synthesis of fat
(b)muscle gain because the amino acids will go directly into building muscle
(c)tiredness because amino acids cannot be used to generate energy
(d)excretion of more nitrogenous (ammonia-derived) wastes than with a more balanced diet
13-9Figure Q13-9 represents a cell lining the gut. Draw numbered labeled lines to indicate exactly where inside a cell the following processes take place.
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Figure Q13-9
1.glycolysis
2.citric acid cycle
3.conversion of pyruvate to activated acetyl groups
4.oxidation of fatty acids to acetyl CoA
5.glycogen breakdown
6.release of fatty acids from triacylglycerols
7.oxidative phosphorylation
13-10Fill in the spaces in the table below. For steps 1, 4, 5, and 8, name the correct substrates, enzyme, or products. For all the other steps, name the enzyme and draw the missing structure.
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13-11Which of the following processes do not take place in the mitochondria?
(a)citric acid cycle
(b)conversion of pyruvate to activated acetyl groups
(c)oxidation of fatty acids to acetyl CoA
(d)glycogen breakdown
13-12Which reaction does the enzyme phosphoglucose isomerase catalyze?
(a)glucose → glucose 6-phosphate
(b)fructose 6-phosphate → fructose 1,6-bisphosphate
(c)glucose 6-phosphate → fructose 6-phosphate
(d)glucose → glucose 1-phosphate
13-13What purpose does the phosphorylation of glucose to glucose 6-phosphate by the enzyme hexokinase serve as the first step in glycolysis?
(a)It helps drive the uptake of glucose from outside the cell.
(b)It generates a high-energy phosphate bond.
(c)It converts ATP to a more useful form.
(d)It enables the glucose 6-phosphate to be recognized by phosphofructokinase, the next enzyme in the glycolytic pathway.
13-14A.How does the generation of ATP by oxidative phosphorylation differ from ATP generation by substrate-level phosphorylation?
B.What catabolic process uses substrate-level phosphorylation, and how many ATP molecules are generated in this way in the reaction pathway?
C.Where does oxidative phosphorylation take place, and what other processes are required for this to occur?
13-15Which of the following cells rely exclusively on glycolysis to supply them with ATP?
(a)anaerobically growing yeast
(b)aerobic bacteria
(c)skeletal muscle cells
(d)plant cells
13-16In anaerobic conditions, skeletal muscle produces _____________.
(a)lactate and CO2
(b)ethanol and CO2
(c)lactate only
(d)ethanol only
13-17Anaerobically growing yeast further metabolizes the pyruvate produced by glycolysis to CO2 and ethanol as part of a series of fermentation reactions.
A.What other important reaction occurs during this fermentation step?
B.Why is this reaction (i.e., the answer to part A) essential for the anaerobically growing cell?
ANSWER
A. NADH ---> NAD+
B.Under anaerobic conditions, it is the only means of regenerating the NAD+ required for glycolysis, the main energy-generating pathway of an anaerobically growing yeast cell.
13-18The first energy-generating steps in glycolysis begin when glyceraldehyde 3-phosphate undergoes an energetically favorable reaction in which it is simultaneously oxidized and phosphorylated by the enzyme glyceraldehyde 3-phosphate dehydrogenase to form 1,3-bisphosphoglycerate, with the accompanying conversion of NAD+ to NADH. In a second energetically favorable reaction catalyzed by a second enzyme, the 1,3-bisphosphoglycerate is then converted to 3-phosphoglycerate, with the accompanying conversion of ADP to ATP. Which of the following statements is true?
(a)The reaction glyceraldehyde 3-phosphate → 1,3-bisphosphoglycerate should be inhibited when levels of NADH fall.
(b)The δG° for the oxidation of the aldehyde group on glyceraldehyde 3-phosphate to form a carboxylic acid is more negative than the δG° for ATP hydrolysis.
(c)The high-energy bond to the phosphate group in glyceraldehyde 3-phosphate contributes to driving the reaction forward.
(d)The cysteine side chain on the enzyme is oxidized by NAD+.
13-19The simultaneous oxidation and phosphorylation of glyceraldehyde 3-phosphate forms a highly reactive covalent thioester bond between a cysteine side chain (reactive group –SH) on the enzyme (glyceraldehyde 3-phosphate dehydrogenase) and the oxidized intermediate (see arrow in Figure Q13-19A). If the enzyme had a serine (reactive group –OH) instead of a cysteine at this position, which could form only a much lower-energy bond to the oxidized substrate (see arrow in Figure Q13-19B), how might this new enzyme act?
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Figure Q13-19
(a)It would oxidize the substrate and phosphorylate it without releasing it.
(b)It would oxidize the substrate but not release it.
(c)It would phosphorylate the substrate on the 2 position instead of the 1 position.
(d)It would behave just like the normal enzyme.
13-20In the absence of oxygen, yeast cells can switch to a completely anaerobic metabolism called fermentation. Which of the following is a final product of fermentation in yeast?
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ANSWER
Diagram A
13-21Pyruvate must move from the cytosol into the mitochondria, where it oxidized to form CO2 and acetyl CoA by the pyruvate dehydrogenase complex. How many different enzymes and what total number of polypeptides, respectively, are required to perform this oxidation process in the mitochondrion?
(a)1; 60
(b)3; 3
(c)3; 26
(d)3; 60
13-22In the absence of oxygen, mammalian cells will endure for a short time using a process called fermentation. Which of the following is a final product of fermentation in mammalian cells?
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13-23In the reaction cycle involved in the oxidation of pyruvate, what are the advantages of having three enzyme activities contained in a single large complex instead of having three smaller and physically independent enzymes?
ANSWER
the proximity of one enzyme to another increases the overall reaction rate this allows for coordinated control of enzyme activity this allows for channeling of intermediates, minimized side reactions
13-24Glycolysis and the citric acid cycle comprise two different sets of oxidation reactions. The reaction sequence for glycolysis is linear, whereas the reaction sequence for the citirc acid cycle forms a circle. How does this difference in the arrangement of reactions influence the rare of these processes when an excess amount of a single intermediate is added?
13-25Indicate whether the following statements are true or false. If a statement is false, explain why it is false.
A.During glycolysis, glucose molecules are broken down to yield CO2 and H2O.
B.The cleavage of fructose 1,6-bisphosphate yields two molecules of glyceraldehyde 3-phosphate.
C.Anaerobic respiration is not the same as fermentation, as only the former requires an electron-transport chain.
D.When subjected to anaerobic conditions, glycolysis in mammalian cells continues and causes a buildup of pyruvate in the cytosol.
E.The pyruvate dehydrogenase complex catalyzes three different, but linked, enzymatic reactions.
F.Amino acids can be transported into the mitochondria and converted into acetyl CoA.
A: TRUE
13-26The reaction cycle that uses acetyl CoA to generate electron carrier molecules needed in the electron-transport chain is important for powering the cell. Which of the names below is not one of those commonly used to describe this reaction cycle?
(a)tricarboxylic acid cycle
(b)Krebs cycle
(c)o...