Question 1

Which of the following best describes the relationship between photosynthesis and cellular respiration in the ecosystem, as illustrated in the first image?

Accepted Answer

Photosynthesis converts light energy into organic molecules and O2, which are then used in cellular respiration to produce ATP and CO2.

Question 2

Consider the following reaction: $$\mathrm{CH_4$ + 2 O_2$ \rightarrow CO_2$ + 2 H_2O + Energy}. $$Which molecule is oxidized and which is reduced?

Accepted Answer

Methane is oxidized and oxygen is reduced.

Question 3

In the general redox reaction $$\mathrm{Xe^- + Y \rightarrow X + Ye^-}$$, which molecule acts as the reducing agent?

Accepted Answer

Xe^-

Question 4

The equation for cellular respiration is $$\mathrm{C_6H_{12}O_6$ + 6 O_2$ \rightarrow 6 CO_2$ + 6 H_2O + Energy}. $$Which molecule is the final electron acceptor in this process?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 5

During glycolysis, which molecule is directly responsible for accepting electrons and becoming reduced?

Accepted Answer

NAD+

Question 6

Which step of cellular respiration accounts for most of the ATP produced from one molecule of glucose?

Accepted Answer

Oxidative phosphorylation

Question 7

Where in the mitochondrion is the electron transport chain located?

Accepted Answer

Inner mitochondrial membrane

Question 8

What is the primary function of ATP synthase in cellular respiration?

Accepted Answer

To synthesize ATP from ADP and inorganic phosphate ($$\mathrm{ADP + P_i \rightarrow ATP}) $$using the proton gradient

Question 9

If oxygen is not available to a cell, what happens to the supply of NAD+ during cellular respiration?

Accepted Answer

NAD+ supply decreases because it cannot be regenerated without oxygen.

Question 10

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation uses organic molecules as the final electron acceptor and produces 2 ATP per glucose.

Question 11

During lactic acid fermentation, what is the purpose of converting pyruvate to lactate?

Accepted Answer

To regenerate NAD+ so glycolysis can continue

Question 12

Which of the following best explains why glycolysis is considered to have an evolutionary basis?

Accepted Answer

Glycolysis can occur without oxygen, suggesting it evolved before oxygen was abundant.

Question 13

In the citric acid cycle, which coenzymes are reduced as a result of oxidation of organic molecules?

Accepted Answer

NAD+ and FAD

Question 14

Which molecule acts as the oxidizing agent during glycolysis?

Accepted Answer

NAD+

Question 15

What is the net ATP yield from glycolysis per molecule of glucose?

Accepted Answer

2 ATP

Question 16

Which of the following is a correct description of substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a substrate to ADP.

Question 17

During oxidative phosphorylation, what is the immediate source of energy used by ATP synthase to synthesize ATP?

Accepted Answer

Proton gradient across the inner mitochondrial membrane

Question 18

Which of the following is a consequence of the electron transport chain being blocked (e.g., by cyanide)?

Accepted Answer

NADH and FADH2 accumulate, and ATP production via oxidative phosphorylation stops

Question 19

In anaerobic respiration, which molecule can act as a final electron acceptor instead of oxygen?

Accepted Answer

Sulfate ion ($$\mathrm{SO_4$^{2-}})$$

Question 20

Approximately what percentage of the energy in a glucose molecule is transferred to ATP during cellular respiration?

Accepted Answer

34%

Cellular Respiration: Mechanisms, Pathways, and Energy Yield

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