Question 1

Which of the following best describes the role of enzymes in microbial metabolism?

Accepted Answer

They lower the activation energy, speeding up chemical reactions without being permanently altered.

Question 2

A bacterium is found to use nitrate ($$NO_3$$^-$$) as its final electron acceptor in respiration. Which of the following statements is most accurate regarding its metabolism?

Accepted Answer

It performs anaerobic respiration and produces less ATP than aerobic respiration.

Question 3

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

Accepted Answer

2 ATP and 2 NADH

Question 4

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The enzyme's active site has a unique 3D shape that only fits specific substrate molecules.

Question 5

A patient’s bacterial infection is identified using a fermentation test containing a carbohydrate, a pH indicator, and a Durham tube. The medium turns yellow and gas is trapped in the tube. What does this indicate about the bacterium?

Accepted Answer

It ferments the carbohydrate, producing acid and gas as byproducts.

Question 6

Which of the following is a correct description of substrate-level phosphorylation?

Accepted Answer

ATP is generated by the direct transfer of a phosphate group from a phosphorylated compound to ADP.

Question 7

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Binding to the active site, preventing the substrate from binding.

Question 8

Which of the following best describes the process of chemiosmosis in ATP generation?

Accepted Answer

Protons are pumped across a membrane, creating a gradient that drives ATP synthesis as they flow back through ATP synthase.

Question 9

Which of the following is NOT a function of coenzymes such as NAD+, NADP+, FAD, or Coenzyme A?

Accepted Answer

Serving as the protein portion of an enzyme.

Question 10

A bacterium is found to be a chemoautotroph. Which of the following best describes its energy and carbon sources?

Accepted Answer

Inorganic chemicals as energy source, CO$$_2 as $$carbon source

Question 11

Which of the following statements about feedback inhibition is correct?

Accepted Answer

The end-product binds allosterically to an early enzyme, decreasing its activity and shutting down the pathway.

Question 12

Which of the following best explains why anaerobic respiration yields less ATP than aerobic respiration?

Accepted Answer

Anaerobic respiration uses inorganic molecules other than oxygen as final electron acceptors, resulting in less complete oxidation of glucose.

Question 13

Which of the following is a correct sequence of events in the mechanism of enzymatic action?

Accepted Answer

Substrate contacts active site, enzyme-substrate complex forms, substrate is transformed, products are released, enzyme is unchanged.

Question 14

A microbe is found to perform anoxygenic photosynthesis. Which of the following is most likely true?

Accepted Answer

It uses $$H_2S as an $$electron donor and does not produce $$O_2.$$

Question 15

Which of the following best describes the function of ribozymes?

Accepted Answer

They are RNA molecules that catalyze specific reactions, such as cutting and splicing RNA.

Question 16

Which of the following metabolic pathways is considered amphibolic?

Accepted Answer

A pathway that functions in both catabolism and anabolism, sharing common intermediates.

Question 17

A bacterial cell is exposed to a noncompetitive inhibitor. What is the most likely effect on the enzyme's activity?

Accepted Answer

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

Question 18

Which of the following best explains why high temperatures can denature enzymes?

Accepted Answer

High temperatures disrupt the enzyme's three-dimensional structure, causing loss of function.

Question 19

Which of the following is a correct description of the fate of fatty acids during lipid catabolism in bacteria?

Accepted Answer

Fatty acids undergo beta-oxidation to form acetyl-CoA, which enters the Krebs cycle.

Question 20

A scientist is studying a bacterium that can grow in the dark using only inorganic chemicals and $$CO_2 as $$its carbon source. Which nutritional classification best fits this organism?

Accepted Answer

Chemoautotroph

Microbial Metabolism: Study Guide and Key Concepts

Study Guide - Practice Questions

Study Guide - Flashcards