Question 1

Which of the following best explains why ATP is considered a more universally useful form of energy for cellular reactions than NADH or FADH$$_2$$?

Accepted Answer

ATP can directly transfer a phosphate group to many different substrates, powering a wide variety of cellular processes.

Question 2

During glycolysis, which of the following occurs?

Accepted Answer

Glucose is split into two molecules of pyruvate, producing a net gain of 2 ATP and 2 NADH.

Question 3

Which stage of aerobic cellular respiration directly produces the most NADH per glucose molecule?

Accepted Answer

Citric acid cycle

Question 4

A patient is exposed to a toxin that blocks the function of Complex IV in the electron transport chain. What is the most immediate effect on cellular respiration?

Accepted Answer

Electrons will not be transferred to oxygen, causing the electron transport chain to stop and ATP production by oxidative phosphorylation to decrease sharply.

Question 5

Which of the following best describes the role of NADH and FADH$$_2 in $$cellular respiration?

Accepted Answer

They act as electron shuttles, carrying high-energy electrons to the electron transport chain.

Question 6

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation regenerates NAD$$^+$$ from NADH, allowing glycolysis to continue in the absence of oxygen.

Question 7

In the absence of oxygen, which process allows human muscle cells to continue producing ATP?

Accepted Answer

Lactic acid fermentation

Question 8

Which of the following is a product of alcohol fermentation that is not produced during aerobic respiration?

Accepted Answer

Ethanol

Question 9

Why is it important that energy is released in small amounts at each electron hand-off along the electron transport chain?

Accepted Answer

It allows the cell to efficiently harness energy to pump protons and build a proton gradient for ATP synthesis.

Question 10

Which of the following best describes the location and function of ATP synthase?

Accepted Answer

Located in the mitochondrial inner membrane, it synthesizes ATP as protons flow through it down their electrochemical gradient.

Question 11

A yeast cell is growing in an environment with no oxygen. Which of the following will occur?

Accepted Answer

The cell will perform alcohol fermentation, producing ethanol and regenerating NAD$$^+.$$

Question 12

Which of the following is true regarding the production of ATP during cellular respiration?

Accepted Answer

Most ATP is produced during oxidative phosphorylation, not during glycolysis or the citric acid cycle.

Question 13

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

Accepted Answer

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

Question 14

If a cell is deprived of oxygen, what will happen to the electron transport chain and ATP production?

Accepted Answer

The electron transport chain will stop, and ATP production by oxidative phosphorylation will cease.

Question 15

Which of the following is a key difference between aerobic respiration and fermentation?

Accepted Answer

Aerobic respiration produces much more ATP per glucose molecule than fermentation.

Question 16

Which process directly results in the production of carbon dioxide ($$\mathrm{CO}_2$$)?

Accepted Answer

Pyruvate oxidation and the citric acid cycle

Question 17

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

A phosphate group is directly transferred from a substrate molecule to ADP, forming ATP.

Question 18

Which of the following statements about the protein complexes (I-IV) in the electron transport chain is correct?

Accepted Answer

They become increasingly electronegative from Complex I to IV, allowing electrons to flow spontaneously toward oxygen.

Question 19

Which of the following is a product of lactic acid fermentation in human muscle cells?

Accepted Answer

Lactate

Question 20

A researcher isolates mitochondria and provides them with all necessary substrates except oxygen. What will happen to the proton gradient across the inner mitochondrial membrane?

Accepted Answer

The proton gradient will dissipate because the electron transport chain cannot function without oxygen.

Cellular Respiration and Fermentation: Step-by-Step Study Guidance

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