Chemistry 2B (Exam #4)

Please answer the following multiple-choice questions, selecting the best answer. Only one answer is correct. Each question is worth 2 points.

1. This pigment molecule that absorbs light energy and passes it on to other molecules of the photosynthesis "light system" is.

(a) hemoglobin

(b) chloroplast

(c) chlorophyll

(d) cytochrome

2. In photosynthesis:

(a) the radiant energy of the sun is converted into chemical energy

(b) light energy may be absorbed by chlorophyll

(c) carbon dioxide is reduced in the synthesis of glucose

(d) all of these

3. In this reaction:

CH₃CH₂OH + NAD⁺ ---> CH₃CHO + NADH + H⁺

(a) a primary alcohol is oxidized to an aldehyde

(b) NAD⁺ is the reducing agent

(c) the alcohol has been reduced to an aldehyde

(d) NAD⁺ has been oxidized

4. The molecules that function as the major sources of reducing power in the cell are:

(a) NADH and FAD

(b) NAD⁺ and FAD

(c) FADH₂and NADH

(d) NAD⁺‚ and FADH₂

5. The majority of ATP synthesis occurs:

(a) during oxidative phosphorylation

(b) in the cytoplasm

(c) when electrons from NAD⁺ and FAD are passed down the electron transport chain

(d) all of these

6. The iron in the iron-heme complex of cytochromes:

(a) always remains in the ferrous (Fe²⁺) state as in hemoglobin

(b) flip-flops between the reduced (Fe²⁺) and oxidized (Fe³⁺) states

(c) goes from Fe²⁺ to Fe³⁺ by the addition of one electron

(d) goes from Fe³⁺ to Fe²⁺ by the loss of one electron

7. Which of the following compounds is not a component of the electron transport chain?

(a) cytochrome c

(b) myoglobin

(c) cytochrome a

(d) coenzyme Q

8. The total number of ATP molecules that can be produced from the combination of one NADH and one FADH2 together in oxidative phosphorylation is

(a) 2

(b) 4

(c) 5

(d) 7

9. Which of the following statements describe(s) cellular respiration?

(a) Cytochromes act as electron carriers.

(b) Oxygen is reduced to water.

(c) The reducing power of NADH and FADH₂ is tied to ATP production.

(d) All of these.

10. The substance of lowest energy among the agents of the respiratory chain is:

(a) oxygen

(b) coenzyme Q

(c) cytochrome b

(d) flavoprotein

11. For which of the following processes is the energy supplied by cleavage of the high-energy phosphate bonds of ATP?

(a) muscle contraction

(b) pumping of substances against a concentration gradient

(c) oxidative phosphorylation

(d) two of these

12. The energy conserved in ATP can be used by the cell to do:

(a) chemical work

(b) osmotic work

(c) mechanical work

(d) all of these

13. Acetyl CoA

(a) is a thioester

(b) contains the B-complex vitamin, pantothenic acid

(c) is an energy-rich compound

(d) all of these

14. The site of glycolysis in the cell is the:

(a) nucleus

(b) cytoplasm

(c) mitochondria

(d) extracellular fluid

15. The first step in glycolysis is the

(a) phosphorylation of glucose to form glucose-6-phosphate

(b) breakdown of glycogen to glucose

(c) synthesis of glycogen from glucose

(d) acetylation of glucose to form acetyl CoA

16. Which of these is not a product of the citric acid cycle?

(a) FAD

(b) CO₂

(c) H₂O

(d) ATP

17. Each turn of the citric acid cycle produces:

(a) one molecule of ATP

(b) one molecule of FADH₂

(c) three molecules of NADH

(d) all of these

18. When aerobic cells are deprived of oxygen the cells produce energy by

(a) the citric acid cycle

(b) glycogenolysis

(c) glycolysis

(d) gluconeogenesis

19. During the catabolism of a molecule of glucose, the majority of the ATP molecules are produced in

(a) citric acid cycle

(b) oxidative phosphorylation

(c) glycolysis

(d) lactic fermentation

20. Glucose is stored in animal cells as:

(a) glucose

(b) glycogen

(c) collagen

(d) acetyl CoA

21. The process by which glucose is converted to glycogen is:

(a) gluconeogenesis

(b) glycogenesis

(c) glycogenolysis

(d) glycolysis

22. Glycogen is stored in _____________ cells.

(a) liver

(b) kidneys

(c) muscle

(d) two of these

23. The second messenger in the regulation of metabolic processes in the cell is:

(a) found within the cell

(b) always an enzyme

(c) acetyl CoA

(d) part of a multienzyme complex

24. A blood sugar level that is below normal is termed:

(a) hypoglycemia

(b) glycosuria

(c) septicemia

(d) hyperglycemia

25. Mobilized fatty acids

(a) must be activated before they can enter liver cells

(b) enter the lymphatic system for transport to cells in need of energy

(c) must be activated before they can pass through the mitochondrial membrane

(d) are a major source of energy for brain cells

26. To enter beta-oxidation, a fatty acid must first be activated by:

(a) formation of the mixed carboxylic-phosphoric acid anhydride by reaction with ATP

(b) reduction with NADH

(c) formation of its fatty acyl CoA

(d) formation of its glycerol ester

27. A chemical intermediate that is central to both carbohydrate metabolism and fatty acid metabolism is:

(a) pyruvate

(b) glucose

(c) acetyl CoA

(d) acetoacetyl CoA

28. The complete degradation of palmitic acid, CH₃(CH₂)₁₄COOH, in the fatty acid spiral (beta oxidation) yields:

(a) 3 acetyl CoA; 3 NADH; 3 FADH₂

(b) 4 acetyl CoA; 3 NADH; 3 FADH₂

(c) 5 acetyl CoA; 4 NADH; 4 FADH₂

(d) 8 acetyl CoA; 7 NADH; 7 FADH₂

29. In the mobilization of fats, glycerol is released from fat cells. Glycerol contributes to energy production by entering the

(a) fatty acid spiral

(b) citric acid cycle

(c) respiratory chain

(d) glycolytic pathway

30. In the human body:

(a) acetyl CoA is readily converted to glucose

(b) brain cells use fatty acids as the major source of carbon nutrients

(c) acetyl CoA cannot be converted to glucose

(d) fatty acids are poor sources of cellular energy

31. During starvation

(a) fatty acids are used for energy production

(b) stored glycogen can supply brain cells with glucose for up to two months

(c) basal metabolism ceases

(d) glucose is the primary energy source

32. Cholesterol is a

(a) steroid and lipid

(b) hormone and protein

(c) ketone body and ester

(d) fatty acid and ester

33. This animal does not have the urea cycle as a metabolic pathway.

(a) dog

(b) human

(c) elephant

(d) fish

34. Which statement is true?

(a) In periods of starvation, amino acids are used for energy production.

(b) Overall, the urea cycle is energy producing.

(c) The only dietary source of nitrogen is protein.

(d) A normal, healthy adult takes in more nitrogen than she excretes.

35. Phenylketonuria (PKU) is:

(a) caused by a defect in amino acid metabolism

(b) treated by increasing phenylalanine in the diet

(c) treated by a phenylalanine deficiency

(d) caused by a phenylalanine deficiency

36. Please draw the structures for each the following compounds:

a-d-Glucose

Citric acid

ATP

fructose-1,6-diphosphate

37. Give the simple equation for photosynthesis using CO₂ and H₂O to produce glucose and O₂.

38. Show what happens (names are okay) when a hormone like epinephrine (adrenaline) binds to a muscle cell receptor and leads to the synthesis of a second messenger.

Answers to Exam 4 Multiple Choice Questions.

1. c

2. d

3. a

4. c

5. a

6. b

7. b

8. c

9. d

10. a

11. d

12. d

13. d

14. b

15. a

16. a

17. d

18. c

19. b

20. b

21. b

22. d

23. a

24. a

25. c

26. c

27. c

28. d

29. d

30. c

31. a

32. a

33. d

34. a

35. a