$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2 \rightarrow 6 \mathrm{CO}_2 + 6 \mathrm{H}_2O + \text{ATP} + \text{heat}$$

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 converts light energy into chemical energy, and cellular respiration releases that energy for cellular work.

Question 2

Which of the following equations correctly represents the overall process of aerobic cellular respiration?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2 ightarrow 6 \mathrm{CO}_2 + 6 \mathrm{H}_2O + 	ext{ATP} + 	ext{heat}$$

Question 3

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

Accepted Answer

Oxidative phosphorylation (electron transport chain and chemiosmosis)

Question 4

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

Accepted Answer

$$\mathrm{O}_2$$

Question 5

What is the main purpose of NAD+ in cellular respiration?

Accepted Answer

To function as an oxidizing agent, accepting electrons during redox reactions

Question 6

Which of the following statements about glycolysis is TRUE?

Accepted Answer

Glycolysis produces a net gain of 2 ATP per glucose molecule by substrate-level phosphorylation.

Question 7

In the absence of oxygen, how do cells regenerate NAD+ to allow glycolysis to continue?

Accepted Answer

By fermentation, transferring electrons from NADH to pyruvate or its derivatives

Question 8

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

Accepted Answer

An enzyme transfers a phosphate group from a substrate molecule to ADP, forming ATP.

Question 9

A patient is diagnosed with a mitochondrial disorder that impairs the function of ATP synthase. Which process would be most directly affected?

Accepted Answer

Chemiosmosis during oxidative phosphorylation

Question 10

Which of the following best explains why fats yield more ATP per gram than carbohydrates during cellular respiration?

Accepted Answer

Fats have more hydrogen atoms and electrons, providing more high-energy electrons for the electron transport chain.

Question 11

Which of the following is NOT a product of the citric acid cycle (Krebs cycle) per turn?

Accepted Answer

2 FADH2

Question 12

In lactic acid fermentation, which of the following occurs?

Accepted Answer

Pyruvate is reduced by NADH to form lactate, regenerating NAD+.

Question 13

Which of the following statements about the electron transport chain (ETC) is correct?

Accepted Answer

The ETC uses the energy from electron transfers to pump protons, creating a gradient used by ATP synthase.

Question 14

A bacterium uses sulfate ($$\mathrm{SO}_4$$^{2-}$$) as a final electron acceptor instead of oxygen. What type of respiration is this?

Accepted Answer

Anaerobic respiration

Question 15

Which of the following best describes chemiosmosis?

Accepted Answer

The movement of H+ ions down their gradient through ATP synthase, driving ATP production

Question 16

Why is the actual yield of ATP per glucose molecule in cellular respiration often less than the theoretical maximum of 32 ATP?

Accepted Answer

Some protons leak across the mitochondrial membrane, and the proton-motive force is used for other work.

Question 17

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

Accepted Answer

Fermentation does not use an electron transport chain, while aerobic respiration does.

Question 18

Which of the following is the correct sequence of energy flow during cellular respiration?

Accepted Answer

Glucose → NADH → electron transport chain → proton-motive force → ATP

Question 19

A yeast cell is placed in an anaerobic environment. Which of the following will most likely occur?

Accepted Answer

The cell will perform alcohol fermentation, producing ethanol and CO2.

Question 20

Which of the following best explains why glycolysis is considered one of the most ancient metabolic pathways?

Accepted Answer

It occurs in the cytoplasm and does not require membrane-bound organelles or oxygen.

Cellular Respiration and Fermentation: Mechanisms of Energy Harvest in Cells

Study Guide - Practice Questions