Question 1

Which of the following best describes the main purpose of catabolic pathways in cellular metabolism?

Accepted Answer

To break down complex molecules into simpler ones, releasing energy

Question 2

During glycolysis, what is the net gain of ATP and NADH molecules per molecule of glucose?

Accepted Answer

$$2$$ ATP and $$2$$ NADH

Question 3

Which of the following statements about glycolysis is CORRECT?

Accepted Answer

Glycolysis occurs in the cytosol and does not require oxygen

Question 4

Pyruvate is converted to acetyl CoA before entering the citric acid cycle. Which of the following is NOT a product of this conversion?

Accepted Answer

FADH$$_2$$

Question 5

Which molecule enters the citric acid cycle by combining with oxaloacetate to form citrate?

Accepted Answer

Acetyl CoA

Question 6

What is the total yield of NADH, FADH$$_2$$, and ATP (or GTP) from one glucose molecule after two turns of the citric acid cycle?

Accepted Answer

$$6$$ NADH, $$2$$ FADH$$_2$$, $$2$$ ATP

Question 7

Which of the following best explains why FADH$$_2$$ produces less ATP than NADH when donating electrons to the electron transport chain?

Accepted Answer

FADH$$_2$$ donates electrons at a lower energy level, bypassing the first proton pump

Question 8

In the electron transport chain, what is the final electron acceptor, and what is formed as a result?

Accepted Answer

Oxygen; water

Question 9

Which of the following steps in cellular respiration directly produces the most ATP per glucose molecule?

Accepted Answer

Electron transport chain and chemiosmosis

Question 10

A patient has a genetic defect that prevents the formation of oxaloacetate. Which process would be directly affected?

Accepted Answer

The citric acid cycle would stop because acetyl CoA could not combine with oxaloacetate to form citrate

Question 11

Which of the following is an example of substrate-level phosphorylation?

Accepted Answer

ATP production during glycolysis

Question 12

Which of the following best describes the role of NAD$$^+ in $$cellular respiration?

Accepted Answer

It acts as an electron carrier, accepting electrons during redox reactions

Question 13

If a toxin inhibits the enzyme that converts isocitrate to alpha-ketoglutarate in the citric acid cycle, what would be the immediate consequence?

Accepted Answer

Accumulation of isocitrate and decreased production of NADH

Question 14

Which of the following statements about the electron transport chain is TRUE?

Accepted Answer

It is a series of redox reactions that transfer electrons from NADH and FADH$$_2 to $$oxygen

Question 15

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

Accepted Answer

Glycolysis $$\rightarrow$$ Pyruvate oxidation $$\rightarrow$$ Citric acid cycle $$\rightarrow$$ Electron transport chain

Question 16

A mutation causes a cell to lack functional FAD. Which step in the citric acid cycle would be directly impaired?

Accepted Answer

Oxidation of succinate to fumarate

Question 17

Which of the following best explains why glycolysis is considered an ancient metabolic pathway?

Accepted Answer

It occurs in the cytosol and does not require oxygen, suggesting it evolved before atmospheric oxygen was abundant

Question 18

Which of the following is a direct result of electrons moving through the electron transport chain?

Accepted Answer

Protons are pumped across the inner mitochondrial membrane, creating a proton gradient

Question 19

If a drug blocks the return of protons through ATP synthase, what would be the immediate effect on cellular respiration?

Accepted Answer

ATP production by chemiosmosis would decrease

Question 20

Which of the following best describes the fate of the carbons from glucose during aerobic respiration?

Accepted Answer

They are released as CO$$_2$$ during pyruvate oxidation and the citric acid cycle

Metabolic Pathways: Catabolic Pathways and Cellular Respiration (Chapter 9: Concepts 9.1–9.5)

Study Guide - Practice Questions