Question 1

Which of the following best describes the relationship between photosynthesis and cellular respiration in the context of energy flow in ecosystems?

Accepted Answer

Photosynthesis uses sunlight to convert carbon dioxide and water into organic molecules and oxygen, while cellular respiration breaks down organic molecules using oxygen to produce ATP, carbon dioxide, and water.

Question 2

What is the overall balanced chemical equation for cellular respiration?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP + heat$$

Question 3

During which stage of cellular respiration is the majority of ATP produced?

Accepted Answer

Oxidative phosphorylation

Question 4

Which of the following statements about glycolysis is correct?

Accepted Answer

Glycolysis occurs in the cytosol and results in a net gain of 2 ATP and 2 NADH per glucose molecule.

Question 5

What is the primary role of oxygen in cellular respiration?

Accepted Answer

To accept electrons at the end of the electron transport chain, forming water.

Question 6

If a person is running vigorously and begins to sweat, which of the following best explains why body-cooling mechanisms are necessary during exercise?

Accepted Answer

Only a small fraction of the energy from glucose is captured as ATP; the rest is released as heat, which must be dissipated to maintain homeostasis.

Question 7

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

The direct transfer of a phosphate group from an organic molecule to ADP to form ATP.

Question 8

A glucose-fed yeast cell is moved from an aerobic environment to an anaerobic one. To continue generating ATP at the same rate, how must the rate of glucose consumption change?

Accepted Answer

It must increase, because fermentation produces much less ATP per glucose molecule than aerobic respiration.

Question 9

Which of the following is a correct statement about the citric acid cycle?

Accepted Answer

It completes the breakdown of glucose by oxidizing acetyl CoA to carbon dioxide, producing NADH and FADH2.

Question 10

Brown fat cells are unique because they:

Accepted Answer

Have mitochondria that generate heat by allowing protons to flow freely across the inner mitochondrial membrane, bypassing ATP synthase.

Question 11

Which of the following best explains why oxygen is required for oxidative phosphorylation?

Accepted Answer

Oxygen acts as the final electron acceptor in the electron transport chain, allowing the chain to continue functioning.

Question 12

Which stage of cellular respiration does NOT take place in the mitochondria?

Accepted Answer

Glycolysis

Question 13

In lactic acid fermentation, what is the fate of NADH produced during glycolysis?

Accepted Answer

It is oxidized back to NAD+ as pyruvate is reduced to lactate.

Question 14

Which of the following statements about the use of macromolecules as fuel for cellular respiration is correct?

Accepted Answer

Fats, proteins, and carbohydrates can all be used as fuel, entering cellular respiration at different points.

Question 15

A person on a low-fat diet can still gain weight and store fat because:

Accepted Answer

Excess carbohydrates and proteins can be converted into fat through metabolic pathways.

Question 16

Which of the following is a real-world example of feedback inhibition in cellular respiration?

Accepted Answer

ATP inhibits an early enzyme in glycolysis when cellular energy levels are high.

Question 17

If oxygen is absent, which process allows some cells to continue producing ATP?

Accepted Answer

Fermentation

Question 18

Which of the following best describes the role of NAD+ in cellular respiration?

Accepted Answer

It acts as an electron carrier, accepting electrons during redox reactions and becoming reduced to NADH.

Question 19

A patient with a genetic defect that causes all their brown fat mitochondria to have leaky inner membranes would most likely:

Accepted Answer

Produce less ATP and more heat than normal individuals.

Question 20

Which of the following is a correct comparison between lactic acid fermentation and alcohol fermentation?

Accepted Answer

Both processes regenerate NAD+ from NADH, but lactic acid fermentation produces lactate while alcohol fermentation produces ethanol and CO2.

Cellular Respiration: How Cells Harvest Chemical Energy

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