Question

The smaller reduction potential of a redox couple indicates its stronger tendency to donate electron.

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True

False

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Question 281 pts

Artificial electron acceptors can serve as an antidote for cyanide poisoning.

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True

False

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Question 291 pts

Electron transport, NADH/FADH₂ oxidation, and ATP synthesis are not always directly coupled.

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True

False

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Question 301 pts

According to the latest finding, the complete oxidation of one mole of glucose yields 38 moles of ATP.

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True

False

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Question 311 pts

The driving force for ATP synthesis during oxidative phosphorylation is the proton gradient

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True

False

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Question 321 pts

When an uncoupler like 2,4-dinitrophenol (DNP) is added to freshly prepared mitochondria, increased O₂ consumption would occur:

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True

False

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Question 331 pts

Respiratory quotient (RQ) is the ratio of CO₂ produced per mole of O₂ consumed in the metabolism of a substrate. If a substrate A has a lower RQ than substrate B, catabolism of A uses less oxygen per carbon oxidized than does catabolism of B.

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True

False

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Question 341 pts

Cytochrome c is a one-electron carrier.

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True

False

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Question 351 pts

The pentose pathway only serves to generate NADPH.

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True

False

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Question 361 pts

Glucose 6-phosphate dehydrogenase catalyzes the first oxidative reaction in the pentose pathway.

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True

False

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Question 371 pts

In the non-oxidative pathways, transketolase catalyzes the transfer of a 3-carbon keto fragment from a sugar molecule to an aldo receptor molecule.

Group of answer choices

True

False

Answer 1

27. True. The smaller reduction potential of a redox couple indicates its stronger tendency to donate electron. Reduction potential is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respectively. The higher reduction potential of a chemical species indictaes the tendency to gain electrons from new species.

28. True. Artificial electron acceptor (oxygen, sodium thiosulfate, amyl nitrite, hydroxocobalamin etc) serve as antidote for cyanide poisoning. Cyanide binds to a3 portion of cytochrome oxidase (complex IV) of the mitochondrial electron transport chain and prevents cells from using oxygen, causig rapid death. For example, sodium thiosulfate acts as a sulfur donar for th enzyme rhodanese which transfers the sulfur to cyanide generating thiocyanate, a relatively non-toxic product.

29. False. Electron transport, NADH/FADH2 oxidation and ATP synthesis are always directly coupled. Electron transport chain is a series of proton-acceptors and electron-acceptors associated with the inner membrane of mitochondria. NADH passes its 2 electrons to firts proton acceptor and 2 H+ are pumped out in intermembrane space of mitochondria. The remaining acceptors pump out 2 more H+ pairs to intermembrane space using energy from downhill moving electron pair. Therefore 3 proton pairs are pumped by using the energy of 1 NADH. 3 H+ pairs or 1 NADH produce 2.5 ATP molecules. FADH2 passes its electrons to second acceptor and only 2 H+ pairs are pumped out. Hence only 1.5 ATP molecules are formed per FADH2.Oxygen is the terminal acceptor of electrons and H+.

30. False. According to latest findings the complete oxidation of one mole of glucose yield 36 moles of ATP.

Net ATP synthesized in glycolysis:

2NADH2: 6 ATPs (3 ATPs per NADH)

Subsrtate level phosphorylation: 2 ATPs

Total ATPs = 8 ATPs

But 2 ATPs are used while transporting NADH + H+ fromed from glycolysis from the cytoplasm through inner mitochondrial membrane.

Therefor Total ATP = 6 ATPs

Net ATP synthesized in Kerb's cycle:

8 NADH2: 24 ATPs (No shuttle system operates as link and Kerb's cycle operates within mitochondrial matrix)

2 FADH2: 4 ATPs (1.5 ATP per FADH2)

Substrate level phosphorylation: 2 ATPs

Total ATPs: 30

So total ATPs produced in complete oxidation of 1 glucose molecule is 6 + 30 = 36 ATPs.

31. True. The driving force for ATP synthesis during oxidative phosphorylation is proton gradient. The proton gradient is formed across the inner mitochondrial membrane which drives the synthesis of ATP via chemiosmosis.

32. True. When an uncoupler like 2,4-dinitrophenol (DNP) is added to freshly prepared mitochondria, increased O2 consumption would occur. DNP decreases formation of high energy phosphate bonds in mitochondria. The increase in oxygen consumption is due to uncoupling of oxidative and phosphorylative processes.

33. False. Molecules having higher respiratory quotients require less oxygen to be fully metabolized. Whereas molecules having lower respiratory quotients require more oxygen for their complete metabolism.

34. True. Cytochrome c is one electron carrier. Unlike other cytochromes, cytochrome c is highly water-soluble and is an essential component of the electron transport chain. It is capable of undergoing oxidation and reduction as its iron atom converts between the ferrous and ferric forms, but does not bind oxygen.

35. True. The primary purpose of pentose phosphate pathway is the generation of reducing equivalents in the form of NADPH which is used in reductive biosynthesis (such as fatty acid synthesis) within the cells.

36. True. Glucose 6-phosphate dehydrogenase is responsible for the first oxidative step of pentose phosphate phatway, a series of chemical reactions that convert glucose to another sugar ribose-5-phosphate.

37. False. Transketolase is an enzyme of both non-oxidative pathway, the pentose phosphate pathway in all organisms and the Calvin cycle of photosynthesis. it catalyzes the transfer of a 2-carbon keto fragment from a sugar molecule (D-xylulose-5-phosphate) to an aldo receptor molecule (D-ribose-5-phosphate) to form 7-carbon ketose (sedoheptulose-7-phosphate).