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Question (21)

QN0036042

During respiration, glucose is first broken down into

(A) carbon dioxide
(B) pyruvate
(C) ethanol
(D) lactic acid

Correct Answer: B

Explanation:

The first step of glucose breakdown produces the three-carbon molecule pyruvate in the cytoplasm.

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Question (22)

QN0036043

If oxygen is unavailable in yeast, pyruvate is converted into

(A) glucose and oxygen
(B) ethanol and carbon dioxide
(C) lactic acid and oxygen
(D) water and glucose

Correct Answer: B

Explanation:

Yeast performs anaerobic respiration, producing ethanol and carbon dioxide.

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Question (23)

QN0036044

A runner suddenly performs strenuous exercise and develops muscle cramps. According to the chapter, which change can explain this?

(A) Accumulation of lactic acid due to insufficient oxygen
(B) Formation of ethanol in muscles
(C) Complete stopping of respiration
(D) Excess production of starch

Correct Answer: A

Explanation:

When oxygen is insufficient in muscle cells, pyruvate can be converted into lactic acid, whose buildup causes cramps.

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Question (24)

QN0036045

Why does aerobic respiration generally release much more energy than anaerobic respiration?

(A) Glucose is broken down more completely
(B) It does not involve pyruvate
(C) It occurs without oxygen
(D) It produces starch

Correct Answer: A

Explanation:

In aerobic respiration, pyruvate is further broken down in the presence of oxygen, releasing considerably more energy.

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Question (25)

QN0036046

A glucose molecule contains six carbon atoms. During the first stage of its breakdown, it forms pyruvate containing

(A) 2 carbon atoms
(B) 3 carbon atoms
(C) 4 carbon atoms
(D) 6 carbon atoms

Correct Answer: B

Explanation:

Glucose is a six-carbon molecule and is first broken down into the three-carbon molecule pyruvate.

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Question (26)

QN0036047

If one pyruvate molecule undergoes aerobic breakdown according to the pathway described in the chapter, how many carbon dioxide molecules are produced?

(A) 1
(B) 2
(C) 3
(D) 6

Correct Answer: C

Explanation:

One three-carbon pyruvate molecule is broken down to give three molecules of CO₂.

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Question (27)

QN0036048

Why is ATP called the energy currency of the cell?

(A) It stores genetic information
(B) It provides usable energy for cellular activities
(C) It transports oxygen
(D) It forms the cell wall

Correct Answer: B

Explanation:

Energy released during respiration is used to make ATP, which then supplies energy for cellular processes.

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Question (28)

QN0036049

The energy released when the terminal phosphate linkage of ATP is broken is approximately

(A) 3.05 kJ/mol
(B) 30.5 kJ/mol
(C) 305 kJ/mol
(D) 0.305 kJ/mol

Correct Answer: B

Explanation:

The chapter gives approximately 30.5 kJ/mol for this energy release.

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Question (29)

QN0036050

At night, a plant is not performing photosynthesis. Which gas exchange is expected to be the major activity?

(A) Oxygen release only
(B) Carbon dioxide elimination due to respiration
(C) Carbon dioxide absorption for photosynthesis
(D) No gas exchange

Correct Answer: B

Explanation:

At night, photosynthesis does not occur, so respiration results in CO₂ release.

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Question (30)

QN0036051

A fish is placed in water containing relatively little dissolved oxygen. Why does it breathe faster than a terrestrial animal?

(A) Water contains more oxygen than air
(B) Dissolved oxygen in water is relatively low
(C) Fish do not use oxygen
(D) Fish perform only anaerobic respiration

Correct Answer: B

Explanation:

Dissolved oxygen is fairly low compared with oxygen available in air, so aquatic organisms breathe faster.

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Question (21)

During respiration, glucose is first broken down into

Explanation:

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Question (22)

If oxygen is unavailable in yeast, pyruvate is converted into

Explanation:

Link:

Question (23)

A runner suddenly performs strenuous exercise and develops muscle cramps. According to the chapter, which change can explain this?

Explanation:

Link:

Question (24)

Why does aerobic respiration generally release much more energy than anaerobic respiration?

Explanation:

Link:

Question (25)

A glucose molecule contains six carbon atoms. During the first stage of its breakdown, it forms pyruvate containing

Explanation:

Link:

Question (26)

If one pyruvate molecule undergoes aerobic breakdown according to the pathway described in the chapter, how many carbon dioxide molecules are produced?

Explanation:

Link:

Question (27)

Why is ATP called the energy currency of the cell?

Explanation:

Link:

Question (28)

The energy released when the terminal phosphate linkage of ATP is broken is approximately

Explanation:

Link:

Question (29)

At night, a plant is not performing photosynthesis. Which gas exchange is expected to be the major activity?

Explanation:

Link:

Question (30)

A fish is placed in water containing relatively little dissolved oxygen. Why does it breathe faster than a terrestrial animal?

Explanation:

Link:

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