Becker World of the Cell 8th Edition Test Bank Jeff Hardin

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Becker World of the Cell 8th Edition Test Bank Jeff Hardin

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Beckers World of the Cell, 8e (Hardin/Bertoni/Kleinsmith)
Chapter 9 Chemotrophic Energy Metabolism: Glycolysis and Fermentation

Multiple Choice Questions

1) The breakdown of glucose to pyruvate by a cell is an example of a(n) ________ reaction.
A) anabolic
B) aerobic
C) catabolic
D) amphibolic
E) synthesis
Answer: C

2) An energy-liberating pathway is considered to be
A) metabolic.
B) anabolic.
C) catabolic.
D) hydrogenation.
E) all of the above
Answer: C

3) A phosphoanhydride bond
A) is a high-energy bond.
B) has a standard free energy of hydrolysis of -7.3 kcal/mol.
C) is broken by hydrolysis.
D) both choices A and B
E) choices A, B, and C
Answer: E

4) The negatively charged phosphates of ATP influence one another by
A) relative hydration.
B) charge repulsion.
C) resonance hybridization.
D) dehydrogenation.
E) all of the above
Answer: B

5) Which of the following best describes the special high-energy bond of ATP?
A) phosphoester
B) phosphoanhydride
C) hydrogen
D) ionic
E) hydrogenation
Answer: B

6) Which term best describes the nitrogenous base adenine plus the sugar ribose?
A) adenine
B) adenosine
C) adenosine diphosphate
D) adenosine triphosphate
E) C followed by A or B
Answer: B
7) Three hypothetical phosphorylated compounds (A, B, and C) are involved in energy metabolism. Standard free energies of hydrolysis for A = 13.1 kcal/mol, for B = -2.7 kcal/mol, and for C = 6.7 kcal/mol.
What is the sequence in which these molecules could most exergonically phosphorylate?
A) A, B, C
B) A, C, B
C) B, C, A
D) C, B, A
E) C followed by A or B
Answer: B

8) Oxidation in biological systems is usually accompanied by
A) repulsion.
B) hydrogenation.
C) dehydrogenation.
D) resonance stabilization.
E) all of the above
Answer: C

9) Which of the following is true of NAD+?
A) It is derived from vitamin E.
B) It serves as an electron source for biological oxidation.
C) It is a coenzyme.
D) It releases an adenosine to become NADH.
E) It represents the reduced form of niacin.
Answer: C

10) All of the following are coenzymes except
A) NAD.
B) NADP.
C) FAD.
D) coenzyme A.
E) pyruvate dehydrogenase.
Answer: E

11) Oxygen is toxic to
A) strict anaerobes.
B) strict aerobes.
C) aerotolerant organisms.
D) facultative anaerobes.
E) all of the above
Answer: A

12) During the first phase of glycolysis, ATP is used to form what type of bond with glucose?
A) phosphoester
B) phosphoanhydride
C) substrate-level phosphorylation
D) dehydrogenation
E) hydrogenation
Answer: A
13) The enzyme ________ is associated with the cytoplasmic portion of the glucose transporter.
A) hexokinase
B) glucose phosphorylase
C) gluconase
D) hexose phosphorylase
E) none of the above
Answer: A

14) The gross output of ATP from glycolysis is ________, whereas the net output of ATP is ________.
A) 2; 1
B) 4; 2
C) 4; 1
D) 6; 4
E) 2; 4
Answer: B

15) In glycolysis, the product(s) of the enzyme aldolase is (are)
A) beta-hydroxy carbonate.
B) dihydroxyacetone phosphate.
C) glyceraldehyde-3-phosphate.
D) choices A and B only
E) choices B and C only
Answer: E

16) Which of the following statements best describes the role of NAD+/NADH in glycolysis?
A) NADH is used to produce energy by directly creating the phosphoanhydride bonds in ATP.
B) NAD+ is used to carry electrons.
C) NADH is capable of pumping ions during glycolysis.
D) NADH is used primarily in substrate-level phosphorylation.
E) all of the above
Answer: B

17) According to your text, glycolysis is divided into three phases. In which phase of glycolysis is ATP not generated?
A) 1
B) 2
C) 3
D) 1 and 2
E) 1, 2, and 3
Answer: A

18) How many enzymatic steps are involved in converting glucose to pyruvate?
A) 3
B) 6
C) 8
D) 10
E) 12
Answer: D
19) The enzyme used to break down fructose-1,6-bisphosphate into two trioses is called
A) hexokinase.
B) phosphoglucoisomerase.
C) triose phosphate isomerase.
D) enolase.
E) aldolase.
Answer: E

20) In glycolysis, which of the following molecules is oxidized to form 1,3-bisphosphoglycerate?
A) 3-phosphoglycerate
B) 2-phosphoglycerate
C) glyceraldehyde-3-phosphate
D) glucose
E) glucose-6-phosphate
Answer: C

21) Which glycolytic enzyme uses ATP as a substrate?
A) alcohol dehydrogenase
B) phosphoglucoisomerase
C) aldolase
D) hexokinase
E) triose phosphate isomerase
Answer: D

22) At which enzymatic step of glycolysis is water a product?
A) 3
B) 5
C) 6
D) 9
E) 10
Answer: D

23) Both the phosphorylation of intermediates and the formation of ATP in glycolysis are examples of
A) substrate-level phosphorylation.
B) product-level phosphorylation.
C) oxidative phosphorylation.
D) anabolic phosphorylation.
E) aerobic phosphorylation.
Answer: A

24) In the first step of glycolysis, glucose can be phosphorylated because
A) a phosphoanhydride bond has higher energy of hydrolysis than a phosphoester bond.
B) the transfer of a phosphate from ATP to glucose is exergonic.
C) both the number 2 and 3 carbons can be spontaneously phosphorylated.
D) the ketosugar is rapidly phosphorylated at the carbon 1 hydroxyl group.
E) both choices A and B
Answer: E
25) Glucose is transported in the bloodstream to cells in all parts of your body. In cells, glucose has four main fates. Which of the following is not one of those fates?
A) Glucose is transformed into sucrose.
B) Glucose is catabolized to carbon dioxide and water.
C) Glucose is converted to lactate.
D) Glucose is used to synthesize glycogen.
E) Glucose is converted to acetyl CoA to make body fat.
Answer: A

26) Which of the following is not a fate of pyruvate within a cell?
A) fermentation
B) anaerobic respiration
C) gluconeogenesis
D) alanine biosynthesis
E) all of the above
Answer: E

27) During strenuous exercise, you may notice that your muscles burn. Which of the following statements best explains this phenomenon?
A) Proteins are being digested to provide energy.
B) Carbon dioxide is building up in muscle and changing the pH.
C) Without oxygen, pyruvate is being converted to lactic acid.
D) ADP is accumulating, which produces a burning sensation.
E) Pyruvic acid causes muscle pain.
Answer: C

28) Pyruvate is the end-product of glycolysis. Many organisms, such as anaerobic bacteria, can only produce energy by glycolysis; therefore, pyruvate has no more potential for ATP generation for these organisms. Rather than simply excrete pyruvate, this molecule is changed to another molecule such as lactate. In these organisms, why is pyruvate changed to lactate and excreted, rather than simply excreted?
A) Pyruvate export requires more energy than lactate.
B) Electrons (and protons) are added to pyruvate to make lactate.
C) NAD+ is regenerated as pyruvate is changed to lactate.
D) Substrate level phosphorylation changes pyruvate to lactate.
E) both choices B and C
Answer: E

29) Which of the following is not a fermentation product?
A) ethanol
B) lactate
C) propionate
D) dihydroxyacetone
E) butyrate
Answer: D
30) Which of the following is not a product of fermentation?
A) lactate
B) CO2
C) ethanol
D) NAD+
E) sucrose
Answer: E

31) The purpose of the fermentation process is the
A) regeneration of NAD+.
B) generation of additional energy in the form of ATP.
C) generation of additional reducing equivalents.
D) production of novel compounds, such as inorganic acids.
E) all of the above
Answer: A

32) The process of glucose synthesis is called
A) glycolysis.
B) gluconeogenesis.
C) aglycolysis.
D) glucogenesis.
E) both choices B and C
Answer: B

33) Within animal cells, glycolysis and gluconeogenesis must not occur at the same time. Therefore, regulation is important. Which of the following molecules is least important in the regulation of glycolysis and gluconeogenesis?
A) NADH
B) fructose-2,6-bisphosphate
C) ATP/ADP
D) acetyl CoA
E) phosphofructokinase-2
Answer: A

34) The cycle in which lactate is removed from muscle tissue and returned to the liver to produce glucose is called
A) gluconeogenesis.
B) glycolysis.
C) fermentation.
D) the Calvin cycle.
E) the pyruvate recovery cycle.
Answer: A

35) Which of the following is not an allosteric inhibitor of an enzyme in the glycolytic pathway?
A) acetyl CoA
B) glucose-6-phosphate
C) citrate
D) fructose-2,6-bisphosphate
E) ATP
Answer: D

36) Glycolytic enzymes have been found to have roles in all of the following except
A) transcriptional repression.
B) apoptosis inhibition.
C) transcriptional activator.
D) GTP hydrolysis.
E) cell migration.
Answer: D

37) Glycolytic enzymes also function in which of the following processes?
A) cell division
B) glycolysis
C) apoptosis
D) growth factors
E) all of the above
Answer: E

38) Which of the following is not a final electron acceptor in anaerobic respiration?
A) sulfur
B) hydrogen
C) iron
D) nitrate
E) pyruvate
Answer: E

39) All of the following are directly used as alternative substrates for glycolysis except
A) galactose.
B) mannose.
C) ribose.
D) fructose.
E) both choices A and C
Answer: C

40) A key regulator of both glycolysis and gluconeogenesis is
A) hexokinase.
B) glyceraldehyde-3-phosphate.
C) alanine.
D) coenzyme (CoA).
E) fructose-2, 6-biophosphate.
Answer: A

Matching Questions

Match the reactant in glycolysis on the left with the appropriate enzyme on the right.

A) phosphofructokinase
B) phosphoglycerokinase
C) fructase
D) phosphoglyceromutase
E) pyruvate kinase
F) phosphoglycerase
G) glucose kinase
H) PEP kinase
I) hexokinase
J) aldolase
K) fructose dehydrogenase

1) glucose
2) fructose-6-phosphate
3) fructose-1,6-bisphosphate
4) phosphoenolpyruvate
5) 1,3-bisphosphoglycerate
6) 3-phosphoglycerate

Answers: 1) I 2) A 3) J 4) E 5) B 6) D

Match the reactant in gluconeogenesis on the left with the appropriate enzyme on the right.

A) hexokinase
B) phosphoenolpyruvate carboxykinase
C) oxaloacetate kinase
D) aldolase
E) pyruvate carboxylase
F) pyruvate kinase
G) phosphoglyceromutase
H) fructose-1,6-bisphosphatase
I) glucose-6-phosphatase

7) pyruvate
8) oxaloacetate
9) fructose-1,6-bisphosphate
10) glucose-6-phosphate
11) 2-phosphoglycerate

Answers: 7) E 8) C 9) H 10) I 11) G

Short Answer Questions

1) ________ is the direct transfer of a phosphate to ADP, forming ATP.
Answer: Substrate-level phosphorylation

2) ________ describes an organism that can function in an aerobic or anaerobic environment.
Answer: Facultative

3) Reduction is defined as the addition of ________. In biological systems, these are usually accompanied by protons in a process called ________.
Answer: electrons; hydrogenation

4) Oxidation is defined as the removal of ________. In biological systems, these are usually accompanied by protons in a process called ________.
Answer: electrons; dehydrogenation

5) Resonance ________ describes a condition in which extra electrons are delocalized over all possible bonds.
Answer: stabilization

6) ________ (NAD+) is the most common coenzyme involved in energy metabolism.
Answer: Nicotinamide adenine dinucleotide

7) The ________ is the link between glycolysis in muscle cells and gluconeogenesis.
Answer: Cori cycle

8) Glycolysis, also called the ________ pathway, is a ________-step reaction sequence that converts glucose into ________.
Answer: glycolytic; 10; pyruvate

9) The coenzyme ________ must interact with pyruvate before fermentation by-products are produced.
Answer: NADH

10) When we eat dairy products, we need ________, the enzyme used to hydrolyze ________ into glucose and galactose. In the absence of this enzyme, we may experience cramps and diarrhea, a condition called ________.
Answer: lactase; lactose; lactose intolerance

11) The three reasons that phosphoanhydride bonds are so exergonic are: ________, ________, and ________.
Answer: charge repulsion; resonance stability; entropy increase

12) During hydrolysis of ATP, it loses a(n) ________, which results in an increase in entropy.
Answer: proton

13) In mammals, four isomers of the glycolytic enzyme ________ have increased expression in tumor cells.
Answer: hexokinase
Inquiry

1) Individuals with diabetes mellitis (sugar diabetes) are often asked to avoid consuming sugar. If they do consume sugar, it is recommended that the sugar be fructose rather than sucrose or glucose.

a. From what you know about the absorption and metabolism of sugars, can you suggest why fructose is the preferred sugar for diabetics?
b. Can you suggest why sucrose is not recommended for diabetics?
c. Why would diabetics be urged to avoid foods that are high in starch?
Answer:
a. While glucose is actively transported from the small intestine, fructose is not. Even though fructose is readily converted to glucose, the slower absorption (passive transport) of fructose will allow for more moderate changes in blood glucose.
b. In the small intestine, sucrose will quickly be converted to glucose and fructose by sucrase. The active transport of glucose will yield a sharp increase in blood glucose.
c. Starch is a polymer of glucose. Although starch is digested more slowly than sucrose, it will still yield an increase in blood sugar.

2) Galactosemia is a genetic defect in which an individual is unable to correctly metabolize galactose. This results in high galactose levels in the blood and galactose-1-phosphate in the tissues.
a. If you were a physician treating a person with this genetic disorder, what suggestions would you make to avoid high galactose levels in the blood?
b. Galactosemia is often a problem in infants. Why would infants be more likely to develop galactosemia?
c. From what you know about the metabolism of galactose can you suggest why galactosemia is more common than fructosemia?
d. Galactosemia is a genetic defect that results from a mutation that results in high levels of galactose-1-phosphate in the blood. The individual is unable to make fully functioning enzymes to metabolize galactose but can still metabolize starch and glycogen. Can you suggest a possible candidate for the flawed enzyme?
Answer:
a. Treatment includes removing galactose from the diet. Lactose should also be avoided since it is metabolized to glucose and galactose.
b. Infants are more likely to have lactose in their diet.
c. There are five enzymatic steps in the transformation of galactose to glucose-6-phosphate. Since metabolism of galactose is more complex, the pathway is more apt to have errors.
d. The enzymes most likely to be involved would be uridyl transferase, UDP-galactose epimerase, or UDP-glucose pyrophosphorylase. Galactokinase is probably not involved because the product of the reactions that it catalyzes is present in tissues (galactose-1-phosphate). The enzyme in the fifth step, phosphoglucomutase, is probably not involved since it is also important in starch and glycogen metabolism, which is not usually a problem for those with galactosemia.

3) Compare and contrast ethanol and lactic acid fermentation pathways.
Answer: Both pathways are a means whereby NAD+ is regenerated. In the case of lactic acid fermentation, pyruvate is the final electron acceptor in the process. In the case of ethanol, pyruvate is decarboxylated to form acetaldehyde; acetaldehyde is the final electron acceptor, forming ethanol.
4) You are studying carbohydrate metabolism in a newly identified bacterial species, which you note grows exclusively on carbohydrate sucrose. How would the sucrose (a disaccharide) be utilized exclusively in glycolysis?
Answer: Sucrose is cleaved into glucose and fructose. Both monosaccharides can directly enter the glycolytic pathway as glucose-6-phosphate and fructose-6-phosphate, respectively.

5) Hereditary fructose intolerance is an autosomal recessive genetic disorder characterized by the lack of the enzyme aldolase B. Symptoms include convulsions, excessive sleepiness, irritability, vomiting, and hypoglycemia. What intermediate accumulates in these individuals, and how may this be associated with the observed symptoms?
Answer: Aldolase B is responsible for the conversion of fructose-1-phosphate to dihydroxyacetone phosphate and glyceraldyde-3-phosphate, which are able to be channeled into glycolysis. During times when sucrose, sorbitol, or fructose are consumed, fructose-1-phosphate accumulates, which can result in hypoglycemia, etc.

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