Bmb Exam 4

Front 1

1. The proton motive force generated by the electron transport chain:
A. includes a pH gradient component.
B. Includes an electrical-potential-gradient (charge separation) component.
C. Is used for active transport processes.
D. Is used to synthesize ATP.
E. Has all of the above.

Back 1

E. Has all of the above.

Front 2

2. The overall yield of ATP from glucose is lower when cells using the glycerol- phosphate shuttle than cells using the malate-aspartate shuttle. Why?
A. Cells using the glycerol-phosphate shuttle only degrade glucose anaerobically
B. The use of glycerol-3-phosphate shuttle reduces the overall yield by 2 (two) moles of ATP because of its entry point in the electron transport chain.
C. Cells using the malate-aspartate shuttle to transfer reducing power of NADH into the mitohondrial transport the full reducing power of NADH from cytosol to the mitochondria.
D. A and B
E. B and C

Back 2

E. B and C

Front 3

3. The electron transport chain contains four membrane complexes, but only three of them participate directly in proton pumping, thus establishing an electrochemical gradient across the inner mitochondrial membrane. Select the answer that lists the three proton pumping complexes.
A. Complexes I, II, and III
B. Complexes I, II and IV
C. Complexes II, III and IV
D. Complexes I, III and IV.

Back 3

D. Complexes I, III and IV.

Front 4

4. Which of the following sequences is correctly ordered from least to most affinity for electrons?
A. Cytochrome c >Coenzyme Q > Cytochrome a
B. FAD > NAD >Coenzyme Q
C. Cytochrome a >Cytochrome c > FAD > Coenzyme Q
D. NAD > Cytochrome a >Coenzyme Q
E. Cytochrome a> Cytochrome c > NAD
F. NAD > CoQ > Cytochrome a

Back 4

F. NAD > CoQ > Cytochrome a

Front 5

5. Match the following chemical to its effect on electron transport and oxidative phosphorylation: Dinitrophenol
A. Stops NAD+-linked oxidation although FAD-linked oxidation can still occur if a suitable substrate is added,. In these conditions, P/O ratio would not be higher than 2.
B. Electron transport can resume if a suitable substrate is added but P/O ratio cannot be higher than 1.
C. ATP/ADP translocase is inhibited.
D. Oxygen uptake increases, protons can diffuse freely across the inner mitochondrial membrane disrupting the proton gradient.
E. ATP synthesis stops, immediately followed by a stop in oxygen uptake.

Back 5

D. Oxygen uptake increases, protons can diffuse freely across the inner mitochondrial membrane disrupting the proton gradient.

Front 6

6. Which of the following is the PRIMARY effect of a deficiency in superoxide dismutase?
A. Damage to cellular components due to an increase in hydrogen peroxide
B. Damage to cellular components due to an increase in the concentration of oxygen radicals
C. Disruption of the proton gradient across the inner mitochondria membrane
D. Cytochrome c oxidase is inactivated
E. None of the above

Back 6

B. Damage to cellular components due to an increase in the concentration of oxygen radicals

Front 7

7. Respiratory coupling or control is defined as:
A. Regulation of oxygen consumption by oxaloacetate availability
B. Regulation of electron transport by availability of NAD
C. Inhibition of oxygen uptake by dinitrophenol
D. Regulation of electron transport by ADP availability
E. Regulation of oxygen consumption by TCA cycle activity

Back 7

D. Regulation of electron transport by ADP availability

Front 8

8. In the electron transport chain, which two electron carrier transfers electrons to one electron carriers?
A. Iron-sulfur proteins
B. NADH
C. Ubiquinol
D. Heme A
E. Cytochrome C
F. NADPH

Back 8

C. Ubiquinol

Front 9

9. Antimycin A blocks electron transfer between cytochromes b and c1. If intact mitochondria were incubated with antimycin A, excess NADH, and an adequate supply of O2, which of the following would be found in the oxidized state?
A) Coenzyme Q
B) Cytochrome a3
C) Cytochrome b
D) Cytochrome g
E) Cytochrome h

Back 9

B) Cytochrome a3

Front 10

10. When the delta G'° of the ATP synthesis reaction is measured on the surface of the ATP synthase enzyme, it is found to be close to zero. This is thought to be due to:
A) A very low energy of activation.
B) Enzyme-induced oxygen exchange.
C) Higher affinity of ADP relative to ATP by the enzyme.
D) Higher affinity of ATP binding relative to ADP by the enzyme.
E) None of the above.

Back 10

D) Higher affinity of ATP binding relative to ADP by the enzyme.

Front 11

11. The oxidation of a particular hydroxy substrate to a keto product by mitochondria has a P/O ratio of less than 2. The initial oxidation step is very likely a (an):
A) oxidation of a flavoprotein.
B) oxidation of a pyridine nucleotide.
C) reduction of a flavoprotein.
D) reduction of a pyridine nucleotide.
E) reduction of cytochrome a3.

Back 11

A or C

Front 12

12. Place the following respiratory-chain components in their proper sequence or electron flow with the first complex having the lowest reduction potential.
A. Cytochrome c => NADH-Q reductase => Cytochrome oxidase => ubiquinone => Cytochrome c reductase
B. Cytochrome c reductase => Cytochrome c => NADH-Q reductase => Cytochrome oxidase => ubiquinone
C. NADH-Q reductase => ubiquinone => Cytochrome c reductase => Cytochrome c => Cytochrome oxidase
D. NADH-Q reductase => Cytochrome oxidase => ubiquinone => Cytochrome c reductase => Cytochrome c
E. Cytochrome oxidase => Cytochrome c => Cytochrome c reductase => Ubiquinone => NADH-Q reductase

Back 12

C. NADH-Q reductase => ubiquinone => Cytochrome c reductase => Cytochrome c => Cytochrome oxidase

Front 13

13. The Standard reduction potentials (E'°) are for the following half reactions are given.
Fumarate + 2H+ + 2e- → succinate E'° = +0.031 V
FAD + 2H+ + 2e- → FADH2 E'° = -0.219 V
If you mixed succinate, fumarate, FAD and FADH2 together, all at 1M concentrations and in the presence of succinate dehydrogenase, which of the following would happen initially?
A. Fumarate and succinate would become oxidized; FAD and FADH2 would become reduced.
B. Fumarate would be reduced, FADH2 would become oxidized. XXXXX
C. No reaction would occur because all reactants and products are already at their standard concentrations.
D. Succinate would become oxidized, FAD would become reduced.
E. Succinate would become oxidized, FADH2 would be unchanged because it is a cofactor.

Back 13

B. Fumarate would be reduced, FADH2 would become oxidized.

Front 14

14. During oxidative phosphorylation, the proton motive force that is generated by electron transport is used to:
A) create a pore in the inner mitochondrial membrane.
B) generate the substrates (ADP and Pi) for the ATP synthase.
C) induce a conformational change in the ATP synthase.
D) oxidize NADH to NAD + .
E) reduce O2 to H2O.

Back 14

C) induce a conformational change in the ATP synthase.

Front 15

15. Which subunit(s) of the ATP synthase complex rotate(s) relative to the membrane in the binding-change model?
A) Alpha
B) Beta
C) Alpha and beta
D) Alpha, beta, and gamma
E) Gamma

Back 15

E) Gamma

Front 16

16-22. Match the compounds with their inhibitory function.
16. Dinitrophenol
17. Rotenone
18. FCCP
19. Oligomycin
20. Atractyloside
21. Amytal
22. CN¯, CO
A. Inhibition of ADP-ATP translocase
B. Inhibition of cytochrome reductase (complex III)
C. Uncoupling of electron transport and Oxidative Phosphorylation
D. Inhibition of ATP synthase
E. Inhibition of NADH - Q Reductase (complex I)
F. Blocks electron flow in cytochrome oxidase (complex IV)

Back 16

16. Dinitrophenol C
17. Rotenone E
18. FCCP C
19. Oligomycin D
20. Atractyloside A
21. Amytal E
22. CN¯, CO F

Front 17

23-25. Match the major units of the ATP-synthesizing system (in A through C) with the appropriate components and functions (23-25).
23. Contains the proton channel
24. Contains the catalytic sites for ATP synthesis
25. Contains γ and ε subunits

A. F0
B. Stalk between F0 and F1
C. F1

Back 17

23. Contains the proton channel A
24. Contains the catalytic sites for ATP synthesis C
25. Contains γ and ε subunits B

Front 18

26. Accessory pigments are able to absorb light and transfer the absorbed energy to the chlorophylls in a process know as “exciton transfer.” The accessory pigments in higher plants are
A. Phycoerythrobilin
B. Phycocyanobilin
C. Lutein
D. beta-carotene
E. B and C
F. A and D
G. D and C
H. Phycoerythrin
I. H and D

Back 18

G. D and C

Front 19

27. Which of the following statements about the light reactions in photosynthetic plants is false?
A) A membrane-bound ATPase couples ATP synthesis to electron transfer.
B) No CO2 is fixed in the light reactions.
C) The ultimate electron acceptor is O2.
D) The ultimate source of electrons for the process is H2O.
E) There are two distinct photosystems, linked together by an electron transfer chain.

Back 19

C) The ultimate electron acceptor is O2.

Front 20

28. Photosynthetic phosphorylation and oxidative phosphorylation appear to be generally similar processes, both consisting of ATP synthesis coupled to the transfer of electrons along an electron carrier chain. Which of the following is not true of both processes?
A) Both contain cytochromes in their electron carrier chains.
B) Both processes are associated with membranous elements of the cell.
C) Both use oxygen as a terminal electron acceptor.
D) Each represents the major route of ATP synthesis in those cells in which it is found.
E) Protons are pumped from the inside to the outside of both mitochondria and chloroplast membranes

Back 20

C) Both use oxygen as a terminal electron acceptor.

Front 21

29. In what order do the following five steps occur in the photochemical reaction centers?
1) Excitation of the chlorophyll a molecule at the reaction center
2) Replacement of the electron in the reaction center chlorophyll
3) Light excitation of antenna chlorophyll molecule
4) Passage of excited electron to electron-transfer chain
5) Exciton transfer to neighboring chlorophyll
A. 1-2-3-4-5
B. 3-2-5-4-1
C. 3-5-1-4-2
D. 4-2-3-5-1
E. 5-4-3-2-1

Back 21

C. 3-5-1-4-2

Front 22

30. In the photolytic cleavage of water by the oxygen-evolving complex 2H2O => 4 H+ + 4e– + O2 , how many photons of light at P680 are required?
A) 1
B) 2
C) 4
D) 6
E) 8

Back 22

C) 4

Front 23

31. Which one of the following statements about photophosphorylation is false?
A) It can be uncoupled from electron flow by agents that dissipate the proton gradient.
B) The difference in pH between the luminal and stromal side of the thylakoid membrane is 3 pH units.
C) The luminal side of the thylakoid membrane has a higher pH than the stromal side.
D) The number of ATPs formed per oxygen molecule is about three.
E) The reaction centers, electron carriers, and ATP-forming enzymes are located in the thylakoid membrane.

Back 23

C) The luminal side of the thylakoid membrane has a higher pH than the stromal side. XXXXX

Front 24

32. Cyclic electron flow in chloroplasts produces:
A) ATP and O2, but not NADPH.
B) ATP, but not NADPH or O2 .
C) NADPH, and ATP, but not O2 .
D) NADPH, but not ATP or O2 .
E) O2, but not ATP or NADPH.

Back 24

B) ATP, but not NADPH or O2 .

Front 25

33. Which is the correct answer? 3-(3,4 dichlorophenyl)-1,1-dimethylurea (DCMU) inhibits photosynthesis by
A. inhibition of electron flow from water to photosystem II
B. inhibition of cyclic photosynthesis
C. inhibition of cytochrome b6f reduction by photosystem II
D. inhibition of photosystem I reduction of ferredoxin
E. direct inhibition of photophosphorylation

Back 25

C. inhibition of cytochrome b6f reduction by photosystem II

Front 26

34. In Photosystem II the correct sequence of flow of electrons from P680 is
A Q, Chl a, Qa, Qb,Pheo a, cyt b6f
B. Chl a, Q, Qa, Ferredoxin, cyt b6f, Pheo a,
C. Chl a, Qa, Qb,Pheo a, Q, PC
D. Chl a, Pheo a, Qa, Qb, Q, cyt b6f
E. Chl a, Qa, Qb, cyt b6f, Pheo a, Q

Back 26

D. Chl a, Pheo a, Qa, Qb, Q, cyt b6f

Front 27

35. Which equation correctly summarizes the carbon fixation reactions of photosynthesis?
A. 6H2O + 6CO2 ==> 6O2 + C6H12O6
B. 6CO2 + 12NADPH + 18ATP + 12H+ ==>12NADP+ + 18ADP + 18Pi + C6H1206
C. 6H20 + 6ADP + 6Pi + 6NADP ==> 602 + 6ATP + NADPH + 6H+
D. 2H20 ==> 02 + 4H+ + 4e-
E. 2C303H5 + C02 ==> 2C303H3 + H20 + CH20

Back 27

B. 6CO2 + 12NADPH + 18ATP + 12H+ ==>12NADP+ + 18ADP + 18Pi + C6H1206

Front 28

36. Ribulose-1,5-bisphosphate carboxylase/oxygenase is arguably the most important enzyme on earth because nearly all life is dependent, ultimately, on its action. The reactions catalyzed by this enzyme are influenced by:
A. pH.
B. substrate concentration.
C. Mg 2+ concentration.
D. temperature.
E. all of the above.

Back 28

E. all of the above.

Front 29

37. Activation of Fructose 1,6 - Bis Phosphatase (FBPase) activity during the light reaction occurs by
A. formation of reduced Fd which reduces Thioredoxin which reduces FBPase
B. decrease of Mg++ in the stroma and increase of pH
C. increase of Mg++ in the stroma and decrease of pH
D. direct reduction of FBPase by NADPH
E. none of the above

Back 29

A. formation of reduced Fd which reduces Thioredoxin which reduces FBPase

Front 30

38. CO2 fixation in C4 plants results first in the synthesis of ________ in the __________ cell and eventually synthesis of malate and then transport of malate into the ______________ cell. Then CO2 fixation occurs via the reaction
A. P-enol-pyruvate, bundle sheath, mesophyll, ribulose bis-P carboxylase
B. Oxaloacetate, mesophyll, bundle sheath, ribulose bis-P carboxylase
C. Oxaloacetate, bundle sheath, mesophyll,PEP carboxylase
D. Pyruvate, mesophyll, bundle sheath, PEP carboxylase
E. 3-P-glycerate, mesophyll, bundle sheath, ribulose bis-P carboxylase
F. P-enolpyruvate, mesophyll, bundlesheath, ribulose bis-P carboxylase
G. Pyruvate, bundle sheath, mesophyll, pyruvate di - kinase

Back 30

B. Oxaloacetate, mesophyll, bundle sheath, ribulose bis-P carboxylase

Front 31

39. Which is the incorrect statement? Photorespiration
A. involves enzymatic reactions in chloroplast, peroxisomes and mitochondrion and transport of metabolites between them
B. is initiated by the oxygenation of Ribulose bisphosphate by Rubisco
C. is supressed by high O2 concentrations
D. is supressed in C4 plants
E. increases with temperature

Back 31

C. is supressed by high O2 concentrations

Front 32

40-43. Match the component to the location.
40. cytosol
41. Chloroplast stroma
42. Inner chloroplast membrane
43. Thylakoid membrane

A. Sucrose synthesis
B. Enzymes of Calvin cycle
C. Triose-P/Pi translocator
D. PSI and PSII

Back 32

40. cytosol A
41. Chloroplast stroma B
42. Inner chloroplast membrane C
43. Thylakoid membrane D

Front 33

44. The compound that condenses with CO2 in the first reaction of carbon dioxide assimilation is:
A. 3-phosphoglycerate.
B. ribose 1,5-bisphosphate.
C. ribulose 1,5-bisphosphate.
D. ribulose 5-phosphate.
E. rubisco.

Back 33

C. ribulose 1,5-bisphosphate.

Front 34

45. When transketolase acts on fructose 6-phosphate and glyceraldehyde 3-phosphate, the products are:
A. 3-phosphoglycerate and glyceraldehyde 3-phosphate.
B. 3-phosphoglycerate and two molecules of glyceraldehyde 3-phosphate.
C. dihydroxyacetone phosphate and glucose 6-phosphate.
D. xylulose 5-phosphate and erythrose 4-phosphate.
E. xylulose 5-phosphate and ribose 5-phosphate.

Back 34

D. xylulose 5-phosphate and erythrose 4-phosphate.

Front 35

46. Which of these chloroplast enzymes is not regulated by light?
A. Fructose 1,6-bisphosphatase
B. Glyceraldehyde-phosphate dehydrogenase
C. Ribulose 5-phosphate kinase
D. Sedoheptulose 1,7-bisphosphatase
E. All of the above are regulated by light.

Back 35

E. All of the above are regulated by light.

Front 36

47. The carbon assimilation (“dark”) reactions of photosynthetic plants:
A. are driven ultimately by the energy of sunlight.
B.are important to plants, but ultimately of little significance for bacteria and animals.
As they cannot occur in the light.
C. yield (reduced) NADH.
D. yield ATP, which is required for the light reactions.
E. In the leaf occur at night as well as in the dark

Back 36

A. are driven ultimately by the energy of sunlight.

Front 37

48. The three subcellular organelles involved in the phosphoglycolate salvage pathway are:
A. endoplasmic reticulum, chloroplast, and mitochondrion.
B. nucleus, endoplasmic reticulum, and chloroplast.
C. golgi apparatus, chloroplast, and mitochondrion.
D. mitochondrion, peroxisome, and chloroplast.
E. peroxisome, endoplasmic reticulum, and chloroplast.

Back 37

D. mitochondrion, peroxisome, and chloroplast.

Front 38

49. The regulatory enzyme of starch synthesis is, and it is activated by and inhibited by .
A. Starch synthase, glucose-6-P, 3-Phosphoglycerate
B. ADP-glucose pyrophosphorylase, 3-Phosphoglycerate, phosphate
C. UDP-glucose pyrophosphorylase, fructose-6-P, PEP
D. ADP-glucose pyrophosphorylase, glucose-6-P, phosphate
E. UDP-glucose pyrophosphorylase, 3-Phosphoglycerate, phosphate
F. Starch synthase, 3-phosphoglycerate, phosphate

Back 38

B

Front 39

50. Sucrose is synthesized in the reaction catalyzed by where and
react to form . The reaction is activated by .
1. fructose 6-P
2. sucrose synthase
3. ADP-glucose
4. glucose 6-P
5.inorganic phosphate 6. covalent modification
7. sucrose 6-P8. sucrose
9. Sucrose 6-P synthetase
10. UDP-glucose

A. 2, 4, 3, 8,10
B. 9,4, 2, 8, 5
C. 9, 1, 10, 7, 4
D. 2,1,10,7, 5

Back 39

E. 9, 1, 10, 8, 5

C