Question 1

Which of the following best describes the chemiosmotic mechanism of ATP generation in cellular respiration?

Accepted Answer

ATP is generated as protons flow down their electrochemical gradient through ATP synthase, driven by a proton gradient established by the electron transport chain.

Question 2

In the reaction: $$\mathrm{CH_3CHO + NADH + H^+ \rightarrow CH_3CH_2OH + NAD^+}$$, which substance is being reduced?

Accepted Answer

Acetaldehyde

Question 3

Why must NADH be reoxidized to NAD$$^+ in $$cells?

Accepted Answer

To allow glycolysis to continue by providing NAD$$^+ as an $$electron acceptor.

Question 4

Which of the following compounds has the greatest amount of energy available for a cell?

Accepted Answer

Glucose

Question 5

Which of the following is the best definition of the Krebs cycle?

Accepted Answer

A series of chemical reactions in which NADH is produced from the oxidation of pyruvic acid.

Question 6

Which culture produces the most lactic acid?

Accepted Answer

E. coli growing in glucose broth at 35°C without O$$_2$$ for 5 days

Question 7

Which culture produces the most ATP?

Accepted Answer

E. coli growing in glucose broth at 35°C with O$$_2$$ for 5 days

Question 8

Which culture uses NAD$$^+$$?

Accepted Answer

Both a and b

Question 9

Which culture uses the most glucose?

Accepted Answer

E. coli growing in glucose broth at 35°C without O$$_2$$ for 5 days

Question 10

How is ATP an intermediate between catabolism and anabolism?

Accepted Answer

ATP stores energy from catabolic reactions and releases it to drive anabolic reactions.

Question 11

What is the main difference between a coenzyme and a cofactor?

Accepted Answer

A coenzyme is an organic molecule, while a cofactor can be either an organic molecule or a metal ion.

Question 12

What happens to an enzyme when the temperature is above its optimal range?

Accepted Answer

The enzyme denatures, losing its functional shape and activity decreases.

Question 13

Which of the following best describes feedback inhibition?

Accepted Answer

The end product of a metabolic pathway inhibits an enzyme involved early in the pathway.

Question 14

Which of the following is a real-life example of competitive inhibition?

Accepted Answer

Sulfanilamide inhibiting folic acid synthesis by competing with para-aminobenzoic acid (PABA) for the active site of DHPS enzyme.

Question 15

Which of the following best explains why Streptococcus grows slowly even under ideal conditions?

Accepted Answer

It lacks a complete electron transport chain and relies on fermentation, which yields less ATP.

Question 16

Why does injection of streptokinase not cause a streptococcal infection in patients?

Accepted Answer

Streptokinase is purified and does not contain live bacteria.

Question 17

Which of the following best describes the effect of a noncompetitive inhibitor on an enzyme?

Accepted Answer

It binds to an allosteric site, changing the enzyme's shape and reducing its activity.

Question 18

Which of the following equations represents the net ATP yield from aerobic respiration of one molecule of glucose in prokaryotes?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + 38ATP}$$

Question 19

Which of the following is NOT a way that ATP is generated in cells?

Accepted Answer

Hydrolysis of glucose

Chapter 5 Microbial Metabolism & Enzyme Regulation Study Guide

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