Question 1

Which of the following statements best distinguishes aerobic respiration from fermentation?

Accepted Answer

Aerobic respiration requires oxygen as the final electron acceptor, whereas fermentation does not utilize an electron transport chain.

Question 2

Which molecule is oxidized and which is reduced in the following cellular respiration equation? 
$$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} \rightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O}$$

Accepted Answer

Glucose is oxidized; oxygen is reduced.

Question 3

During glycolysis, which enzyme catalyzes the splitting of a 6-carbon sugar into two 3-carbon molecules?

Accepted Answer

Aldolase

Question 4

Which of the following best describes the function of NAD+/NADH in cellular respiration?

Accepted Answer

NADH donates electrons to the electron transport chain, facilitating ATP production.

Question 5

Why is the electron transport chain organized as a series of stepwise reactions rather than a single transfer of electrons to oxygen?

Accepted Answer

Stepwise transfer allows for gradual release of energy, which can be harnessed to pump protons and generate ATP.

Question 6

Which of the following equations represents the reduction of NAD+ during glycolysis?

Accepted Answer

$$\mathrm{NAD^+} + 2\mathrm{e^-} + 2\mathrm{H^+} \rightarrow \mathrm{NADH} + \mathrm{H^+}$$

Question 7

Which process directly regenerates ATP from a phosphorylated substrate and ADP?

Accepted Answer

Substrate-level phosphorylation

Question 8

What is the net energy output of glycolysis per molecule of glucose?

Accepted Answer

2 ATP, 2 NADH, 2 pyruvate

Question 9

During pyruvate oxidation, which of the following is produced from one molecule of pyruvate?

Accepted Answer

Acetyl-CoA, CO2, NADH

Question 10

Which step in the citric acid cycle involves the conversion of succinyl-CoA to succinate and the production of GTP?

Accepted Answer

The step catalyzed by succinyl-CoA synthetase

Question 11

How can GTP produced in the citric acid cycle be converted to ATP?

Accepted Answer

By direct phosphorylation of ADP by GTP

Question 12

Which complex in the electron transport chain acts as a proton pump and contributes to the H+ gradient?

Accepted Answer

Complex I

Question 13

What is the final electron acceptor in the mitochondrial electron transport chain?

Accepted Answer

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

Question 14

Which of the following best describes chemiosmosis?

Accepted Answer

The diffusion of protons across a membrane to drive ATP synthesis via ATP synthase

Question 15

Why is the exact number of ATP molecules produced from one glucose molecule during cellular respiration not precisely known?

Accepted Answer

The transport of NADH from cytosol to mitochondria can vary, and some protons may leak across the membrane.

Question 16

Which of the following is a key difference between lactic acid fermentation and alcohol fermentation?

Accepted Answer

Alcohol fermentation produces ethanol and CO2, while lactic acid fermentation produces lactate.

Question 17

Which organism is most likely to utilize anaerobic respiration?

Accepted Answer

Certain bacteria that use nitrate as a final electron acceptor

Question 18

Which metabolic pathway allows fatty acids to enter cellular respiration?

Accepted Answer

Beta oxidation, which produces acetyl-CoA from fatty acids

Question 19

What waste product is generated when amino acids are deaminated before entering cellular respiration?

Accepted Answer

Urea

Question 20

Which of the following statements about the evolutionary significance of glycolysis is correct?

Accepted Answer

Glycolysis is a universal pathway found in nearly all organisms, suggesting it evolved early in the history of life.

Cellular Respiration and Fermentation: Study Guide

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