$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy (ATP)}$$

Question 1

Which of the following best describes the main purpose of cellular respiration in eukaryotic cells?

Accepted Answer

To break down glucose and other molecules to produce ATP

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 enzyme is responsible for the phosphorylation of fructose-6-phosphate in glycolysis, and how is it regulated?

Accepted Answer

Phosphofructokinase; inhibited by high levels of ATP

Question 4

What is the fate of pyruvate in eukaryotic cells under aerobic conditions?

Accepted Answer

It is transported into the mitochondria and converted to acetyl CoA

Question 5

Which of the following statements about the citric acid cycle is correct?

Accepted Answer

It oxidizes acetyl CoA to produce $$2$$ $$CO_2$$, $$3$$ NADH, $$1$$ FADH$$_2$$, and $$1$$ ATP (or GTP) per turn

Question 6

What is the primary role of the electron transport chain (ETC) in cellular respiration?

Accepted Answer

To transfer electrons from NADH and FADH$$_2 to $$oxygen, creating a proton gradient

Question 7

Which molecule acts as the final electron acceptor in aerobic respiration, and what is produced as a result?

Accepted Answer

Oxygen; producing water

Question 8

How does ATP synthase produce ATP during oxidative phosphorylation?

Accepted Answer

By using the energy from a proton gradient to phosphorylate ADP

Question 9

Which of the following best explains why fermentation is less efficient than aerobic respiration?

Accepted Answer

Fermentation does not use the electron transport chain, so less ATP is produced per glucose

Question 10

A patient has a genetic defect that prevents the formation of the mitochondrial inner membrane. Which process would be most directly affected?

Accepted Answer

Electron transport and oxidative phosphorylation

Question 11

Which of the following is a correct summary equation for aerobic cellular respiration?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 ightarrow 6CO_2 + 6H_2O + 	ext{energy (ATP)}$$

Question 12

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP synthesis by direct transfer of a phosphate group from a substrate to ADP

Question 13

If a cell is deprived of oxygen, which of the following will immediately stop?

Accepted Answer

Electron transport chain

Question 14

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

Accepted Answer

Lactate

Question 15

Which of the following statements about the regulation of metabolic pathways is correct?

Accepted Answer

Feedback inhibition allows cells to maintain homeostasis by adjusting pathway activity based on product levels

Question 16

A mutation causes phosphofructokinase to lose its regulatory site for ATP. What is the most likely consequence?

Accepted Answer

Glycolysis will be unresponsive to ATP levels and may overproduce ATP

Question 17

Which of the following best explains why oxygen is the most efficient final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen is highly electronegative, allowing a large release of energy when it accepts electrons

Question 18

Which of the following is a correct description of chemiosmosis?

Accepted Answer

The movement of protons down their electrochemical gradient through ATP synthase to drive ATP production

Question 19

Which of the following statements about facultative anaerobes is true?

Accepted Answer

They can switch between aerobic respiration and fermentation depending on oxygen availability

Cellular Respiration and Fermentation: Pathways for Energy Harvest in Cells

Study Guide - Practice Questions