Question 1

The experimental determination of the effectiveness of light of different colors in promoting photosynthesis is called the:

Accepted Answer

A)  absorption spectrum.
B)  action spectrum.
C)  difference spectrum.
D)  reflectance spectrum.
E)  refraction spectrum.F) D) and E)
G) C) and D)

Question 2

Given that ~8 photons are required to produce one molecule of O2,roughly how many photons are required to produce one molecule of glucose.

Accepted Answer

Since the overall reaction of photosynth...

Question 3

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 directly coupled to the:

Accepted Answer

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.F) A) and E)
G) B) and E)

Question 4

Show the path of electrons from photosystem II to NADPH in the chloroplast.What is the source of the energy that moves electrons through this path? Show where oxygen is involved in this pathway.

Accepted Answer

H₂O

P680

Pheophytin

PQA

PQB...

Question 5

When the F1 portion of the ATP synthetase complex is removed from the mitochondrial membrane and studied in solution,it functions as an ATPase.Why does it not function as an ATP synthetase?

Accepted Answer

Like all enzymes,the F₁ subun...

Question 6

Plants carrying out photosynthesis produce O2.Describe the source of this O2,and explain,with chemical equations or schematic diagrams,why O2 production occurs only during daylight hours.

Accepted Answer

O₂ is generated by the splittin...

Question 7

Which one of the following statements about photophosphorylation is false?

Accepted Answer

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.F) A) and B)
G) A) and C)

Question 8

In his studies of alcoholic fermentation by yeast,Louis Pasteur noted that the sudden addition of oxygen (O2)to a previously anaerobic culture of fermenting grape juice resulted in a dramatic decrease in the rate of glucose consumption.This "Pasteur effect" can be counteracted by the addition of 2,4-dinitrophenol (DNP),an uncoupler of oxidative phosphorylation.
(a)Why would the yeast cells consume less glucose in the presence of oxygen? Can you estimate how much less glucose they would use? 
(b)Why would DNP counteract or prevent the Pasteur effect?

Accepted Answer

(a)During aerobic oxidation of glucose,t...

Question 9

Which of the following statements about the chemiosmotic theory is false?

Accepted Answer

A)  Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.
B)  Energy is conserved as a transmembrane pH gradient.
C)  Oxidative phosphorylation cannot occur in membrane-free preparations.
D)  The effect of uncoupling reagents is a consequence of their ability to carry protons through membranes.
E)  The membrane ATPase,which plays an important role in other hypotheses for energy coupling,has no significant role in the chemiosmotic theory.F) B) and C)
G) A) and C)

Question 10

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) Exiton transfer to neighboring chlorophyll

Accepted Answer

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)  5-4-3-2-1F) C) and D)
G) A) and B)

Question 11

Cyclic electron flow in chloroplasts produces:

Accepted Answer

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.F) A) and E)
G) A) and D)

Question 12

Consider a liver cell carrying out the oxidation of glucose under aerobic conditions.Suppose that we added a very potent and specific inhibitor of the mitochondrial ATP synthase,completely inhibiting this enzyme.Indicate whether each of the following statements about the effect of this inhibitor is true or false;if false,explain in a sentence or two why it is false.
____ (a)ATP production in the cell will quickly drop to zero.
____ (b)The rate of glucose consumption by this cell will decrease sharply.
____ (c)The rate of oxygen consumption will increase.
____ (d)The citric acid cycle will speed up to compensate.
____ (e)The cell will switch to fatty acid oxidation as an alternative to glucose oxidation,and the inhibitor will therefore have no effect on ATP production.

Accepted Answer

A) True 
 B)False  False

Question 13

Which of the following is not true of the proton motive force (pmf) ?

Accepted Answer

A)  One component of the pmf is the chemical gradient of protons.
B)  One component of the pmf is the charge gradient of protons.
C)  Generation of the pmf in mitochondria requires succinate.
D)  The pmf is generated by the electron transport chain in mitochondria.
E)  The pmf drives ATP synthesis in mitochondria.F) A) and C)
G) A) and B)

Question 14

Show the path of electrons from ubiquinone (Q or coenzyme Q)to oxygen in the mitochondrial respiratory chain.One of the two compounds (Q and O2)has a standard reduction potential (E'°)of 0.82 V,and the other,0.045 V.Which value belongs to each compound? How did you deduce this?

Accepted Answer

QH₂

cyt b

cyt c₁ ...

Question 15

Photophosphorylation differs from oxidative phosphorylation in that the former requires the input of energy in the form of ___________ to create a good electron donor.In photophosphorylation,electrons flow through a series of membrane-bound carriers including ___________ ,___________ ,and ___________ proteins,whereas ___________ are pumped across a membrane to create an ___________ potential.

Accepted Answer

Light;cytochromes;qu...

Question 16

The compound 2,4-dinitrophenol (DNP),an uncoupler,was briefly used as a weight-loss drug.Some of its effects in people who took the drug included weight loss and higher than normal body temperature.Some people even died.Explain the first two effects of the compound in biochemical terms.

Accepted Answer

The uncoupler allows continuous oxidatio...

Question 17

Describe,in simple diagrams and a few words,the chemiosmotic theory for coupling oxidation to phosphorylation in mitochondria.

Accepted Answer

There are two central elements in the ch...

Question 18

Which of the following statements about energy conservation in the mitochondrion is false?

Accepted Answer

A)  Drugs that inhibits the ATP synthase will also inhibit the flow of electrons down the chain of carriers.
B)  For oxidative phosphorylation to occur,it is essential to have a closed membranous structure with an inside and an outside.
C)  The yield of ATP per mole of oxidizable substrate depends on the substrate.
D)  Uncouplers (such as dinitrophenol) have exactly the same effect on electron transfer as inhibitors such as cyanide;both block further electron transfer to oxygen.
E)  Uncouplers "short circuit" the proton gradient,thereby dissipating the proton motive force as heat.F) A) and B)
G) A) and C)

Question 19

Which of the following is not true about cyclic electron flow?

Accepted Answer

A)  Cyclic electron flow produces more NADPH per photon than noncyclic electron flow.
B)  Cyclic electron flow involves only PSI.
C)  Plastocyanin is required for cyclic electron flow.
D)  Cyclic electron flow leads to the build-up of a proton gradient.
E)  Cyclic electron flow does not produce O2.F) B) and E)
G) B) and D) A

Question 20

In the photolytic cleavage of water by the oxygen-evolving complex [2H2O  →\rightarrow→  4 H+ + 4e- + O2],how many photons of light at a wavelength of 680 nm are required?

Accepted Answer

A)  1
B)  2
C)  4
D)  6
E)  8 F) C) and E)
G) A) and B) C

Exam 19: Oxidative Phosphorylation and Photophosphorylation

The experimental determination of the effectiveness of light of different colors in promoting photosynthesis is called the:

Correct Answer
verified

Given that ~8 photons are required to produce one molecule of O₂,roughly how many photons are required to produce one molecule of glucose.

Correct Answer
verified
Since the overall reaction of photosynth...
View Answer

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 directly coupled to the:

Correct Answer
verified

Show the path of electrons from photosystem II to NADPH in the chloroplast.What is the source of the energy that moves electrons through this path? Show where oxygen is involved in this pathway.

Correct Answer
verified
H₂O P680 Pheophytin PQAPQB...
View Answer

When the F₁ portion of the ATP synthetase complex is removed from the mitochondrial membrane and studied in solution,it functions as an ATPase.Why does it not function as an ATP synthetase?

Correct Answer
verified
Like all enzymes,the F₁ subun...
View Answer

Plants carrying out photosynthesis produce O₂.Describe the source of this O₂,and explain,with chemical equations or schematic diagrams,why O₂ production occurs only during daylight hours.

Correct Answer
verified
O₂ is generated by the splittin...
View Answer

Which one of the following statements about photophosphorylation is false?

Correct Answer
verified

Correct Answer
verified
(a)During aerobic oxidation of glucose,t...
View Answer

Which of the following statements about the chemiosmotic theory is false?

Correct Answer
verified

Correct Answer
verified

Cyclic electron flow in chloroplasts produces:

Correct Answer
verified

Correct Answer
verified
False

Which of the following is not true of the proton motive force (pmf) ?

Correct Answer
verified

Show the path of electrons from ubiquinone (Q or coenzyme Q)to oxygen in the mitochondrial respiratory chain.One of the two compounds (Q and O₂)has a standard reduction potential (E'°)of 0.82 V,and the other,0.045 V.Which value belongs to each compound? How did you deduce this?

Correct Answer
verified
QH₂ cyt b cyt c₁ ...
View Answer

Correct Answer
verified
Light;cytochromes;qu...
View Answer

The compound 2,4-dinitrophenol (DNP),an uncoupler,was briefly used as a weight-loss drug.Some of its effects in people who took the drug included weight loss and higher than normal body temperature.Some people even died.Explain the first two effects of the compound in biochemical terms.

Correct Answer
verified
The uncoupler allows continuous oxidatio...
View Answer

Describe,in simple diagrams and a few words,the chemiosmotic theory for coupling oxidation to phosphorylation in mitochondria.

Correct Answer
verified
There are two central elements in the ch...
View Answer

Which of the following statements about energy conservation in the mitochondrion is false?

Correct Answer
verified

Which of the following is not true about cyclic electron flow?

Correct Answer
verified
A

In the photolytic cleavage of water by the oxygen-evolving complex [2H₂O $\rightarrow$ 4 H⁺ + 4e^- + O₂],how many photons of light at a wavelength of 680 nm are required?

Correct Answer
verified
C

Exam 19: Oxidative Phosphorylation and Photophosphorylation

The experimental determination of the effectiveness of light of different colors in promoting photosynthesis is called the:

Correct AnswerverifiedShow Answer

Given that ~8 photons are required to produce one molecule of O2,roughly how many photons are required to produce one molecule of glucose.

Correct AnswerverifiedSince the overall reaction of photosynth...View AnswerShow Answer

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 directly coupled to the:

Correct AnswerverifiedShow Answer

Show the path of electrons from photosystem II to NADPH in the chloroplast.What is the source of the energy that moves electrons through this path? Show where oxygen is involved in this pathway.

Correct AnswerverifiedH2O P680 Pheophytin PQAPQB...View AnswerShow Answer

When the F1 portion of the ATP synthetase complex is removed from the mitochondrial membrane and studied in solution,it functions as an ATPase.Why does it not function as an ATP synthetase?

Correct AnswerverifiedLike all enzymes,the F1 subun...View AnswerShow Answer

Plants carrying out photosynthesis produce O2.Describe the source of this O2,and explain,with chemical equations or schematic diagrams,why O2 production occurs only during daylight hours.

Correct AnswerverifiedO2 is generated by the splittin...View AnswerShow Answer

Which one of the following statements about photophosphorylation is false?

Correct AnswerverifiedShow Answer

Correct Answerverified(a)During aerobic oxidation of glucose,t...View AnswerShow Answer

Which of the following statements about the chemiosmotic theory is false?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Cyclic electron flow in chloroplasts produces:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedFalse

Which of the following is not true of the proton motive force (pmf) ?

Correct AnswerverifiedShow Answer

Show the path of electrons from ubiquinone (Q or coenzyme Q)to oxygen in the mitochondrial respiratory chain.One of the two compounds (Q and O2)has a standard reduction potential (E'°)of 0.82 V,and the other,0.045 V.Which value belongs to each compound? How did you deduce this?

Correct AnswerverifiedQH2 cyt b cyt c1 ...View AnswerShow Answer

Correct AnswerverifiedLight;cytochromes;qu...View AnswerShow Answer

The compound 2,4-dinitrophenol (DNP),an uncoupler,was briefly used as a weight-loss drug.Some of its effects in people who took the drug included weight loss and higher than normal body temperature.Some people even died.Explain the first two effects of the compound in biochemical terms.

Correct AnswerverifiedThe uncoupler allows continuous oxidatio...View AnswerShow Answer

Describe,in simple diagrams and a few words,the chemiosmotic theory for coupling oxidation to phosphorylation in mitochondria.

Correct AnswerverifiedThere are two central elements in the ch...View AnswerShow Answer

Which of the following statements about energy conservation in the mitochondrion is false?

Correct AnswerverifiedShow Answer

Which of the following is not true about cyclic electron flow?

Correct AnswerverifiedA

In the photolytic cleavage of water by the oxygen-evolving complex [2H2O →\rightarrow→ 4 H+ + 4e- + O2],how many photons of light at a wavelength of 680 nm are required?

Correct AnswerverifiedC

Correct Answer
verified

Given that ~8 photons are required to produce one molecule of O₂,roughly how many photons are required to produce one molecule of glucose.

Correct Answer
verified
Since the overall reaction of photosynth...
View Answer

Correct Answer
verified

Correct Answer
verified
H₂O P680 Pheophytin PQAPQB...
View Answer

When the F₁ portion of the ATP synthetase complex is removed from the mitochondrial membrane and studied in solution,it functions as an ATPase.Why does it not function as an ATP synthetase?

Correct Answer
verified
Like all enzymes,the F₁ subun...
View Answer

Plants carrying out photosynthesis produce O₂.Describe the source of this O₂,and explain,with chemical equations or schematic diagrams,why O₂ production occurs only during daylight hours.

Correct Answer
verified
O₂ is generated by the splittin...
View Answer

Correct Answer
verified

Correct Answer
verified
(a)During aerobic oxidation of glucose,t...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
False

Correct Answer
verified

Show the path of electrons from ubiquinone (Q or coenzyme Q)to oxygen in the mitochondrial respiratory chain.One of the two compounds (Q and O₂)has a standard reduction potential (E'°)of 0.82 V,and the other,0.045 V.Which value belongs to each compound? How did you deduce this?

Correct Answer
verified
QH₂ cyt b cyt c₁ ...
View Answer

Correct Answer
verified
Light;cytochromes;qu...
View Answer

Correct Answer
verified
The uncoupler allows continuous oxidatio...
View Answer

Correct Answer
verified
There are two central elements in the ch...
View Answer

Correct Answer
verified

Correct Answer
verified
A

In the photolytic cleavage of water by the oxygen-evolving complex [2H₂O $\rightarrow$ 4 H⁺ + 4e^- + O₂],how many photons of light at a wavelength of 680 nm are required?

Correct Answer
verified
C