$\mathrm{C_6H_{12}O_6} + 6\mathrm{O_2} \rightarrow 6\mathrm{CO_2} + 6\mathrm{H_2O} + \text{energy}$

Question 1

Which of the following best describes the function of brown adipose tissue in humans?

Accepted Answer

It burns fat to produce heat, especially via the action of UCP1 in mitochondria.

Question 2

During cellular respiration, which process directly produces the majority of ATP in eukaryotic cells?

Accepted Answer

Oxidative phosphorylation via chemiosmosis in mitochondria

Question 3

Which equation correctly represents the overall reaction for aerobic cellular respiration of glucose?

Accepted Answer

$\mathrm{C_6H_{12}O_6} + 6\mathrm{O_2} ightarrow 6\mathrm{CO_2} + 6\mathrm{H_2O} + 	ext{energy}$

Question 4

Which statement about the laws of thermodynamics as applied to cells is correct?

Accepted Answer

Energy transformations in cells always increase the total entropy of the universe.

Question 5

What is the role of UCP1 (uncoupling protein 1) in brown adipose tissue mitochondria?

Accepted Answer

It allows protons to re-enter the mitochondrial matrix, dissipating the proton gradient as heat instead of producing ATP.

Question 6

Which of the following is an example of an exergonic reaction in cellular metabolism?

Accepted Answer

Hydrolysis of ATP to ADP and Pi

Question 7

During glycolysis, which molecule is produced as a result of substrate-level phosphorylation?

Accepted Answer

ATP

Question 8

Which process occurs in the absence of oxygen and allows glycolysis to continue by regenerating NAD$^+$?

Accepted Answer

Fermentation

Question 9

If a muscle cell is deprived of oxygen, which pathway will it use to generate ATP and what is the end product?

Accepted Answer

Fermentation; lactic acid

Question 10

Which of the following best explains why stepwise oxidation of glucose in cells is advantageous compared to direct combustion?

Accepted Answer

It enables the cell to capture energy in activated carriers such as ATP and NADH.

Question 11

Which of the following is the correct sequence of stages for energy extraction from food molecules?

Accepted Answer

Breakdown in mouth and gut → breakdown in cytosol → breakdown in mitochondria

Question 12

Which of the following statements about ATP is correct?

Accepted Answer

ATP stores energy in its phosphate bonds, which can be used to drive endergonic reactions.

Question 13

Which of the following reactions is an example of a redox reaction in cellular metabolism?

Accepted Answer

Reduction of NAD$^+$ to NADH during glycolysis

Question 14

Which compartment of the mitochondrion contains the enzymes for the citric acid cycle?

Accepted Answer

Mitochondrial matrix

Question 15

What is the main function of the electron transport chain in mitochondria?

Accepted Answer

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

Question 16

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

Direct transfer of a phosphate group from a substrate to ADP to form ATP

Question 17

Which of the following is a correct comparison between aerobic respiration and fermentation?

Accepted Answer

Aerobic respiration yields more ATP per glucose molecule than fermentation.

Question 18

Which molecule acts as the final electron acceptor in the mitochondrial electron transport chain?

Accepted Answer

O$_2$

Question 19

If the inner mitochondrial membrane becomes permeable to protons, what is the most likely consequence for ATP synthesis?

Accepted Answer

ATP synthesis will decrease because the proton gradient is dissipated.

Question 20

Which of the following best explains why fermentation is necessary in anaerobic conditions?

Accepted Answer

It regenerates NAD$^+$ so glycolysis can continue in the absence of oxygen.

Cellular Energy Extraction and Thermodynamics

Study Guide - Practice Questions