Tuesday, March 2, 2010

Energy Practice Test Answers

Excuse the format if the practice test did not transfer perfect...The images did not transfer....I only have the option to cut and paste...I can not attach the document to the blog!

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) What is the term used for the metabolic pathway in which glucose (C6H12O6) is degraded to carbon dioxide (CO2) and water?

A) cellular respiration

B) glycolysis

C) fermentation

D) citric acid cycle

E) oxidative phosphorylation

3) Which of the following statements concerning the metabolic degradation of glucose (C6H12O6) to carbon dioxide (CO2) and water is (are) true?

A) The breakdown of glucose to carbon dioxide and water is exergonic. .

B) The breakdown of glucose to carbon dioxide and water involves oxidation-reduction or redox reactions.

C) A and B are both correct.

E) none of these are correct.

4) Which of the following statements is (are) correct about an oxidation-reduction (or REDOX) reaction?

A) The molecule that is reduced gains electrons.

B) The molecule that is oxidized loses electrons.

C) The molecule that is reduced loses electrons.

D) The molecule that is oxidized gains electrons.

E) Both A and B are correct.

5) Which statement is not correct with regard to REDOX (oxidation-reduction) reactions?

A) A molecule is reduced if it loses electrons.

B) A molecule is oxidized if it loses electrons.

C) An electron donor is called a reducing agent.

D) An electron acceptor is called an oxidizing agent.

E) Oxidation and reduction always go together.

6) The molecule that functions as the REDUCING AGENT 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.

7) When electrons move closer to a more electronegative atom, what happens?

A) Energy is released.

B) Energy is absorbed.

C) The more electronegative atom is reduced.

D) The more electronegative atom is oxidized.

E) A and C are correct.

8) Which of the following statements describes the results of this reaction?

C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP

A) C6H12O6 is oxidized and O2 is reduced.

B) O2 is oxidized and H2O is reduced.

C) CO2 is reduced and O2 is oxidized.

D) C6H12O6is reduced and CO2 is oxidized.

E) O2 is reduced and CO2 is oxidized.

9) When a glucose molecule loses a hydrogen ATOM (NOT a hydrogen ION) as the result of an REDOX reaction, the molecule becomes

A) dehydrated.

B) hydrated.

C) oxidized.

D) reduced.

E) an oxidizing agent.

10) When a molecule of NAD+ gains a hydrogen ATOM (NOT a hydrogen ION) the molecule becomes

A) hydrated.

B) oxidized.

C) reduced.

D) redoxed.

E) a reducing agent.

11) Which of the following statements about NAD+ is FALSE?

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 a protein during the ETC.

D) NAD+ can receive electrons for use in oxidative phosphorylation.

E) In the absence of NAD+, glycolysis cannot function.

12) In order for NAD+ to remove electrons from glucose or other organic molecules, which of the following must be true?

A) The organic molecule or glucose must be negatively charged in order to reduce the positively charged NAD+.

B) Oxygen must be present to oxidize the NADH produced back to NAD+.

C) The energy released when electrons are removed from the organic molecules must be greater than the energy required to give the electrons to NAD+.

D) A and B are both correct.

E) A, B, and C are all correct.

13) Where does glycolysis take place?

A) mitochondrial matrix

B) mitochondrial outer membrane

C) mitochondrial inner membrane

D) mitochondrial intermembrane space

E) cytosol

14) The ATP made directly by glycolysis is generated by

A) substrate-level phosphorylation.

B) electron transport.

C) photophosphorylation.

D) chemiosmosis.

E) oxidation of NADH to NAD+.

15) 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

16) 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

17)Which of the following statements about glycolysis is false?

A) Glycolysis has steps involving oxidation-reduction reactions.

B) The enzymes of glycolysis are located in the cytosol of the cell.

C) Glycolysis can operate in the complete absence of O2.

D) The end products of glycolysis are CO2 and H2O.

E) Glycolysis makes ATP exclusively through substrate-level phosphorylation.

Refer to Figure 9.1 to answer the questions 18-22.

Figure 9.1 illustrates some of the steps (reactions) of glycolysis in their proper sequence. EACH STEP IS LETTERED. USE THESE LETTERS TO ANSWER THE QUESTIONS.

Figure 9.1

18) Which step shows a split of one molecule into two smaller molecules? B

19) In which step is an inorganic phosphate added to the reactant?

Answer: C

20) In which reaction does an intermediate pathway become oxidized?

Answer: C

21) Which step involves an endergonic reaction?

Answer: A

22) Which step consists of a phosphorylation reaction in which ATP is the phosphate source?

Answer: A

23) Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed during glycolysis?

A) 0%

B) 2%

C) 10%

D) 38%

E) 100%

24) 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 and the NADH produced

D) used to phosphorylate fructose to form fructose-6-phosphate.

25) In addition to ATP, what are the end products of glycolysis?

A) CO2 and H2O

B) CO2 and pyruvate

C) NADH, H2O, and pyruvate

D) CO2 and NADH

E) H2O, FADH2, and citrate

26) In glycolysis, for each molecule of glucose oxidized to pyruvate

A) 2 molecules of ATP are used and 2 molecules of ATP are produced.

B) 2 molecules of ATP are used and 4 molecules of ATP are produced.

C) 4 molecules of ATP are used and 2 molecules of ATP are produced.

D) 2 molecules of ATP are used and 6 molecules of ATP are produced.

E) 6 molecules of ATP are used and 6 molecules of ATP are produced.

27) A molecule that is phosphorylated

A) has an increased chemical reactivity; it is primed to do cellular work.

B) has a decreased chemical reactivity; it is less likely to provide energy for cellular work.

C) has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate.

D) has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate.

E) has less energy than before its phosphorylation and therefore less energy for cellular work.

28) 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 CO2, 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A. These three steps result in the formation of

A) acetyl CoA, O2, and ATP.

B) acetyl CoA, FADH2, and CO2.

C) acetyl CoA, FAD, H2, and CO2.

D) acetyl CoA, NADH, and CO2.

E) acetyl CoA, NAD+, ATP, and CO2.

29) Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate?

A) lactate

B) glyceraldehydes-3-phosphate

C) oxaloacetate

D) acetyl CoA

E) citrate

30) During cellular respiration, acetyl CoA accumulates in which location?

A) cytosol

B) mitochondrial outer membrane

C) mitochondrial inner membrane

D) mitochondrial intermembrane space

E) mitochondrial matrix

31) How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of GLUCOSE?

A) 2

B) 4

C) 6

D) 8

E) 10

32) All of the following are functions of the citric acid cycle except

A) production of ATP.

B) production of NADH.

C) production of FADH2.

D) release of carbon dioxide.

E) adding electrons and protons to oxygen, forming water.

33) Carbon dioxide (CO2) 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 (the transition reaction) and the citric acid cycle

C) the citric acid cycle and oxidative phosphorylation

D) oxidative phosphorylation and fermentation

E) fermentation and glycolysis

34) For each molecule of GLUCOSE that is metabolized by GLYCOLYSIS and the KREBS CYCLE, what is the total number of NADH and FADH2 molecules produced?

A) 4

B) 5

C) 6

D) 10

E) 12

35) Cellular respiration harvests the most chemical energy from which of the following?

A) substrate-level phosphorylation

B) chemiosmotic phosphorylation

C) converting oxygen to ATP

D) transferring electrons from organic molecules to pyruvate

E) generating carbon dioxide and oxygen in the electron transport chain

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

Figure 9.2

36) 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

37) Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid?

A) succinate

B) malate

C) citrate

D) α-ketoglutarate

E) isocitrate

38) Starting with one molecule of citrate and ending with oxaloacetate, how many ATP molecules can be formed from oxidative phosphorylation (chemiosmosis)?

A) 1

B) 3

C) 4

D) 11

E) 12

39) 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

40) How many ATP molecules could be made through substrate-level phosphorylation PLUS oxidative phosphorylation if you started with three molecules of succinyl CoA and ended with oxaloacetate? Note: Where in this diagram are we starting? What molecules are made here that will be sent elsewhere? How many ATP will be produced by these molecules in the end? Don’t forget the ATP molecules that are made directly through the process in this diagram.

A) 6

B) 12

C) 18

D) 24

E) 36

41) During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest protein complex?




D) ADP + Pi


42) 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 hydrogen electrons and hydrogen protons, forming water.

C) combine with carbon, forming CO2.

D) combine with lactate, forming pyruvate.

E) catalyze the reactions of glycolysis.

43) In chemiosmotic phosphorylation, what is the most DIRECT source of energy that is used to convert ADP + Pi 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 against their concentration gradient

D) energy released from movement of protons through ATP synthase

E) No external source of energy is required because the reaction is exergonic.

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