review

Oxidizing which of the following substances yields the most energy? A) proteins B) glucose C) fatty acids D) water

C

A new drug was found to decrease Hepatitis B virus. The drug is an analogue of one of the nucleic acid bases of DNA and probably works by being incorporated into the virus and disrupting viral genes during viral DNA replication. However, patients in a clinical trial of the drug began to experience drastic overproduction of lactic acid and liver failure leading to death. The most likely explanation for the problem: A. Incorporation of the drug into mitochondrial DNA disrupts the ability of mitochondria to make ATP. B. The virus with mutations must overproduce lactic acid.

A

Explain why in anaerobic cells the ratio of pyruvate/ lactate is much less than 1 while under aerobic conditions the ratio of pyruvate/ lactate is much greater than 1. A. lactate is produced from pyruvate only under anaerobic conditions B. under anaerobic conditions pyruvate is converted to carbon dioxide C. in anaerobic conditions, pyruvate is converted to glucose using the energy of light D. lactate is the terminal electron acceptor under aerobic conditions E. pyruvate is transported into mitochondria under anaerobic conditions

A

The electron transport chain pumps protons A) out of the mitochondrial matrix. B) out of the intermembrane space and into the matrix. C) out of the mitochondrion and into the cytoplasm. D) out of the cytoplasm and into the mitochondrion.

A

The final electron acceptor in lactic acid fermentation is: A) pyruvate B) NAD+ C) lactic acid D) O2

A

Trematol is a metabolic poison derived from the white snake root. Cows eating this plant concentrate the poison in their milk. The poison inhibits liver enzymes that convert lactic acid to other compounds for metabolism. Why does physical exertion increase symptoms of poisoning by trematol? Why does the pH of the blood decrease in a person who has digested trematol? A. Physical exertion would increase the production of latic acid by fermentation, and the build up of lactic acid decreases blood pH when liver enzymes are blocked. B. Physical exertion increases metabolism, and the electron transport chain pumping H+ out of mitochondria increases blood pH.

A

Which of the following is not a stage of aerobic respiration? A) glycolysis B) pyruvate oxidation C) the Krebs cycle D) electron transport chain

A

Dinitrophenol (DNP) is an uncoupler, or has the ability to separate the flow of electrons and the pumping of H+ ions for ATP synthesis. This means that the energy from electron transfer cannot be used for ATP synthesis. Fifty years ago, DNP was given as a drug to help patients lose weight. Why does this work? Why would this be dangerous? A. Uncoupling the electron transport chain would inhibit fermentation and decrease ATP production, a potentially dangerous situation. B. If electron transport doesn't produce ATP, then much more sugar must be metabolized for energy needs. Very low production of ATP would be lethal.

B

Glycolysis leads to the production of ____________ and two molecules of ATP. In the absence of oxygen, fermentation leads to the production of ______________. Glycolysis plus the citric acid cycle can convert the carbons of glucose to _________ , storing the energy as ATP, _____________ and ___________. A. lactic acid, pyruvate, CO2, NADH, FADH2 B. pyruvate, lactic acid, CO2, NADH, FADH2 C. CO2, NADH, FADH2, lactic acid, pyruvate D. O2, lactic acid, pyruvate, FADH2 E. glucose, lactic acid, CO2, NADH, FADH2

B

In cellular respiration, energy-depleted electrons are donated to an inorganic molecule. In fermentation, what molecule accepts these electrons? A) oxygen B) an organic molecule C) sulfur D) an inorganic molecule other than O2

B

Pyruvate dehydrogenase is a multienzyme complex that catalyzes a series of reactions. Which of the following is not carried out by pyruvate dehydrogenase? A) a decarboxylation reaction B) the production of ATP C) producing an acetyl group from pyruvate D) combining the acetyl group with a cofactor

B

The electrons generated from the Krebs cycle are transferred to ____________ and then are shuttled to _______________. A) NAD+ / oxygen B) NAD+ / electron transport chain C) NADH / oxygen D) NADH / electron transport chain

B

ATP synthase can produce ATP using as a direct energy source: A. energy from the conversion of glucose to pyruvate B. energy from the oxidation of pyruvate producing CO2 and H20 C. energy from a proton gradient established in mitochondria D. energy derived from the breakdown of NADH and FADH2 E. energy from the metabolism of amino acids

C

How many molecules of CO2 are produced for each molecule of glucose that passes through glycolysis and the Krebs cycle? A) 2 B) 3 C) 6 D) 7

C

In the first step of glycolysis, the enzyme hexokinase uses ATP to transfer a phosphate to glucose to form glucose-6-phosphate. The product continues to be oxidized forming pyryvate in glycolysis and is a precursor to acetyl-CoA for the citric acid cycle. Suppose that a cell has only glucose available for energy and that the activity of hexokinase is suddenly stopped in this cell. Which of the following conditions will occur? A. The cell will continue to produce energy from mitochondrial electron transport. B. The cell will continue to produce ATP using the citric acid cycle. C. The cell will ultimately be unable to produce ATP. D. The cell will be forced to switch to fermentation to produce ATP. E. The use of oxygen by the cell will increase.

C

At the end of glycolysis, each molecule of glucose has yielded 2 molecules of _______, 2 molecules of ________, and a net of 2 molecules of _________. A. FAD; NAD+; ADP B. CO2; NAD+; ADP C. lactic acid; ethanol; CO2 D. pyruvate, NADH, ATP E. H2O; CO2; ATP

D

What process of cellular respiration generates the most ATP? A) glycolysis B) oxidation of pyruvate C) Krebs cycle D) chemiosmosis

D

Which steps in glycolysis require the input of energy? A) the glucose priming steps B) the phosphorylation of glucose C) the phosphorylation of fructose 6-phosphate D) All of these steps require the input of energy.

D

As a result of glycolysis, pyruvate oxidation and the citric acid cycle, only a small portion of the energy of glucose has been converted to ATP. At this point, the majority of the usable energy is contained in: A. oxidized electron carriers NAD+ and FAD B. carbon dioxide C. pyruvate D. acetyl coenzyme A E. reduced electron carriers NADH and FADH

E

During a heart attack, blood flowing to the heart muscle is interrupted by blockage of a coronary artery. How would you expect the metabolism in the heart to change? A. oxidative phosphorylation would slow down in the mitochondria B. the rate of production of lactic acid would be stimulated C. the use of glucose by the muscle tissue would increase D. the production of water by mitochondria would be inhibited E. all are expected metabolic changes

E

The major production of ATP during aerobic metabolism occurs when electrons from __________ and _____________ are transferred to _______________. A. FADH2, NADH, H20 B. O2, FADH2, NADH C. FADH2, O2, NADH D. NADH, O2, FADH2 E. FADH2, NADH, O2

E

The terminal electron acceptor during mitochondrial respiration: A. H20 B. NAD+ C. FAD D. ATP E. O2

E

A high concentration of Glucose-6-P is inhibitory to which of the following enzymes ? a) Hexokinase b) Glucokinase c) PFK-1 d) PFK-2 e) All of the above

a

The enzyme that catalyzes first substrate level phosphorylation in glycolysis- a) Produces 3-phosphoglycerate as a product b) Produces ADP from AMP c) Is called glyceraldehyde-3-phosphate dehydrogenase d) Is called phosphofructokinase e) Is the rate limiting enzyme of glycolysis.

a

During fasting state, the insulin to glucagon ratio drops and all of the following occur except- a) Protein kinase A will phosphorylate pyruvate kinase b) The pyruvate kinase step will be activated c) Protein kinase A will phosphorylate phosphofructokinase-2/fructose-2,6-bisphosphatase d) The concentration of fructose-2,6-bisphosphate will decrease e)The liver will not be able to synthesize pyruvate from phosphoenolpyruvate.

b

Pasteur effect is due to inhibition of glycolysis by high concentration of - a) Creatine phosphate b) ATP c) ADP d) AMP e) Pi

b

The enzyme that produces NADH from a triose phosphate in the glycolytic pathway- a) Uses NAD+ and dihydroxyacetone phosphate as substrates b) Produces 1, 3-Bisphosphoglycerate and NADH c) Catalyzes irreversible reaction d) Is called 3-phosphoglycerate kinase e) Uses FADH2 and glyceraldehyde-3-phosphate as substrates

b

The phosphofructokinase-2 enzyme that transfers a phosphate group to fructose-6-phosphate in glycolysis- a) Is active in the phosphorylated form b) Catalyzes a reversible reaction c) Produces fructose-2,6-bisphosphate as a product d) Is the rate limiting enzyme for glycolysis e) Produces ATP as a product.

b

The two major factors determining whether a cell oxidizes glucose by aerobic glycolysis or by anaerobic glycolysis are- a) FADH2 and the number of mitochondria b) NADH and the ATP/ADP ratio c) Ca++ and AMP d) Oxygen pressure and the number of mitochondria e) Presence of low Glucose and high AMP

b

When glucose is converted to lactate by anaerobic glycolysis, the equivalent of ________ ATPs are derived. When glucose is completely oxidized to CO2 by glycolysis, Pyruvate dehydrogenase, and the TCA cycle, the equivalent of _______ ATPs are derived. a)7; 20 b)2; 38 c)7; 32 d)2; 12 e)7; 25

b

Which out of the following statements is not true about aerobic glycolysis ? a) The rate limiting enzyme is phosphofructokinase-1 which converts fructose-6- phosphate to fructose- 1,6-bisphosphate b) The pathway is inhibited allosterically by fructose-2,6-bisphosphate and AMP c) The pathway takes place in mitochondria of every cell d) The pathway produces Pyruvate and NADH e) The pathway begins with glucokinase or hexokinase

b

Choose the incorrect statement about the condition 'When one molecule of glucose is oxidized to 2 molecules of lactate during anaerobic glycolysis'- a) One molecule of ATP is used by the phosphofructokinase-1 reaction b) One molecule of ATP is used by either the glucokinase or hexokinase reaction c) Two molecules of ATP are produced by the Glyceraldehyde -3-P dehydrogenase reaction d) Two molecules of ATP are produced by the pyruvate kinase reaction e) No ATP is produced at the level of lactate dehydrogenase reaction.

c

The ATP/AMP ratio has a major effect upon the rate of ATP production by glycolysis. ATP and AMP bind to allosteric sites on- a) Hexokinase b) Glucokinase c) Phosphofructokinase-1 d) Phosphofructokinase-2 e) 3-phosphoglycerate kinase

c

The enzyme that catalyzes the second substrate level phosphorylation of glycolysis- a) Is called phosphoglyceromutase b) Produces lactate as a product c) Uses phosphoenolpyruvate as a substrate d) Catalyzes a reversible reaction e) Is stimulated by Glucagon.

c

Which of these enzyme reactions is not irreversible in glycolysis? a) Hexokinase b) Glucokinase c) 3-phosphoglycerate kinase d) Phosphofructokinase-1 e) Pyruvate kinase

c

An increased concentration of insulin after meals causes an increase in the rate of glycolytic pathway by all of the following mechanisms except- a) Increase uptake of glucose in adipose tissue and muscle b) Inactivation of the cAMP cascade c) Increased dephosphorylation of enzymes activated by protein kinase A d) Activation of fructose-2,6-bisphosphatase and inhibition of phosphofructokinase-2 e) Induction of Glucokinase and PFK-1

d

Which of the following statements about pyruvate kinase is false - a) Can convert Phosphoenol pyruvate to pyruvate b) Is regulated by feed forward regulation c) Is active in the dephosphorylated form d) Is also involved in gluconeogenesis e) Deficiency causes haemolytic anemia.

d

In the liver, glucagon causes a decrease in the glycolytic pathway by all of the following mechanisms except- a) Increased binding of GTP to G-protein b) Activation of the cAMP cascade c) Increased phosphorylation of enzymes by protein kinase A d) Activation of fructose-2,6-bisphosphatase and inhibition of phosphofructokinase-2 e) Increased binding of fructose-2,6-bisphosphate to phosphofructokinase-1

e