$$\text{Glucose} + 2\,\text{ADP} + 2\,\text{P}_i \rightarrow 2\,\text{Pyruvate} + 2\,\text{ATP} + 2\,\text{NADH}$$

Question 1

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

Accepted Answer

Fermentation does not utilize the electron transport chain, so most of the energy in glucose remains in the fermentation end-products.

Question 2

During lactic acid fermentation, what is the primary role of pyruvic acid?

Accepted Answer

To act as the final electron acceptor, regenerating NAD$$^+$$ for glycolysis.

Question 3

Which of the following equations correctly represents the net ATP yield from glycolysis of one molecule of glucose?

Accepted Answer

$$	ext{Glucose} + 2\,	ext{ADP} + 2\,	ext{P}_i ightarrow 2\,	ext{Pyruvate} + 2\,	ext{ATP} + 2\,	ext{NADH}$$

Question 4

A bacterium is grown in a medium containing glucose but no oxygen. Which metabolic pathway will it most likely use to generate ATP?

Accepted Answer

Fermentation

Question 5

Which of the following is a common end-product of fermentation by Saccharomyces (yeast)?

Accepted Answer

Ethanol and CO$$_2$$

Question 6

In the fermentation test shown in the images, which tube (a-d) indicates acid production with gas formation?

Accepted Answer

Tube (d)

Question 7

Which of the following best describes the fate of NADH produced during glycolysis under anaerobic conditions?

Accepted Answer

It is oxidized back to NAD$$^+$$ during fermentation.

Question 8

Which metabolic pathway is responsible for the breakdown of fatty acids into acetyl-CoA?

Accepted Answer

Beta-oxidation

Question 9

Which of the following best describes the role of the Calvin-Benson cycle in photosynthesis?

Accepted Answer

It fixes CO$$_2$$ into organic molecules.

Question 10

A chemoheterotroph obtains its energy and carbon from which sources?

Accepted Answer

Organic compounds for both energy and carbon

Question 11

Which of the following is a correct summary of the products of noncyclic photophosphorylation?

Accepted Answer

ATP, NADPH, and O$$_2$$

Question 12

Which of the following statements about protein catabolism is correct?

Accepted Answer

Proteins are broken down into amino acids, which can enter the Krebs cycle after deamination.

Question 13

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

Accepted Answer

It occurs in nearly all living organisms and does not require oxygen.

Question 14

Which of the following is the correct sequence of events in the catabolism of a triglyceride?

Accepted Answer

Hydrolysis to fatty acids and glycerol, beta-oxidation of fatty acids, entry of acetyl-CoA into Krebs cycle

Question 15

Which of the following best describes the main function of the electron transport chain in respiration?

Accepted Answer

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

Question 16

Which of the following is a distinguishing feature of cyclic photophosphorylation compared to noncyclic photophosphorylation?

Accepted Answer

Cyclic photophosphorylation only produces ATP and does not generate O$$_2.$$

Question 17

Which of the following best explains why fermentation is important for cells under anaerobic conditions?

Accepted Answer

It allows glycolysis to continue by regenerating NAD$$^+.$$

Question 18

Which of the following is a possible fermentation end-product for Escherichia coli?

Accepted Answer

Ethanol, lactic acid, succinic acid, acetic acid, CO$$_2$$, and H$$_2$$

Question 19

Which of the following best describes the role of glyceraldehyde 3-phosphate (GP) in glycolysis?

Accepted Answer

It is an intermediate that is oxidized to produce NADH and ATP.

Microbial Metabolism: Fermentation, Catabolism, and Photosynthesis

Study Guide - Practice Questions