Question 1

Which of the following best describes the main purpose of the citric acid cycle in cellular respiration?

Accepted Answer

To generate reduced electron carriers (NADH and FADH$$_2) $$for use in the electron transport chain

Question 2

During the oxidation of pyruvate to acetyl CoA, which of the following events does NOT occur?

Accepted Answer

Direct production of ATP

Question 3

Which molecule acts as the final electron acceptor in the electron transport chain during aerobic respiration?

Accepted Answer

O$$_2$$

Question 4

What is the main reason why the electron transport chain releases energy in small steps rather than all at once?

Accepted Answer

To allow the cell to capture energy efficiently for ATP synthesis

Question 5

Which of the following statements about ATP synthase is TRUE?

Accepted Answer

It uses the energy of the proton gradient to synthesize ATP from ADP and inorganic phosphate ($$P_i)$$

Question 6

In the absence of oxygen, which process allows glycolysis to continue by regenerating NAD$$^+$$?

Accepted Answer

Fermentation

Question 7

Which of the following is a byproduct of alcohol fermentation in yeast, and why is it significant in baking?

Accepted Answer

Carbon dioxide ($$CO_2$$); it causes bread to rise

Question 8

Why does lactic acid fermentation occur in human muscle cells during intense exercise?

Accepted Answer

Because oxygen delivery cannot meet ATP demand, so cells regenerate NAD$$^+ to $$continue glycolysis

Question 9

Which of the following best explains why fats yield more ATP than carbohydrates when used as fuel in cellular respiration?

Accepted Answer

Fats are broken down into acetyl CoA, which enters the citric acid cycle multiple times due to long hydrocarbon chains

Question 10

Which enzyme is considered the main regulatory point of glycolysis, and how is it regulated?

Accepted Answer

Phosphofructokinase; inhibited by ATP and citrate, stimulated by AMP

Question 11

Which of the following is NOT a product of one turn of the citric acid cycle?

Accepted Answer

Glucose

Question 12

What is the main function of the proton gradient established by the electron transport chain?

Accepted Answer

To drive the synthesis of ATP via ATP synthase

Question 13

Which of the following statements about substrate-level phosphorylation and oxidative phosphorylation is correct?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group from an organic substrate to ADP

Question 14

If a mutation prevented the formation of coenzyme Q in mitochondria, which process would be directly affected?

Accepted Answer

Transfer of electrons from NADH and FADH$$_2 to $$the electron transport chain

Question 15

Which of the following best explains why the maximum yield of ATP per glucose molecule during cellular respiration is not a precise number?

Accepted Answer

Some ATP is used to transport electrons into the mitochondria, and the proton motive force is used for other work

Question 16

Which of the following is a correct sequence of events in aerobic cellular respiration?

Accepted Answer

Glycolysis → Pyruvate Oxidation → Citric Acid Cycle → Oxidative Phosphorylation

Question 17

Which of the following is TRUE regarding the fate of pyruvate in the absence of oxygen?

Accepted Answer

It is converted to ethanol or lactate to regenerate NAD$$^+$$

Question 18

Which of the following best describes the role of citrate in the regulation of glycolysis?

Accepted Answer

Citrate acts as a negative feedback inhibitor of phosphofructokinase

Question 19

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

Accepted Answer

Alcohol fermentation includes a decarboxylation step, while lactic acid fermentation does not

Bio 100 LEC Chapter 9 Modules 3-6

Study Guide - Practice Questions