Question 1

Which of the following statements best describes the Entner-Doudoroff pathway?

Accepted Answer

It is an ancient pathway found primarily in Gram-negative, obligate aerobic bacteria and yields one ATP per glucose.

Question 2

Which of the following is a primary function of the pentose phosphate pathway in bacteria?

Accepted Answer

To convert 5-carbon sugars into 3- or 6-carbon sugars and provide precursors for nucleotide and amino acid biosynthesis.

Question 3

Which of the following best distinguishes fermentation from anaerobic respiration?

Accepted Answer

Fermentation does not use a respiratory chain, while anaerobic respiration does.

Question 4

During lactic acid fermentation, what is the main purpose of reducing pyruvic acid to lactic acid?

Accepted Answer

To regenerate NAD+ so glycolysis can continue.

Question 5

Which of the following equations correctly represents the breakdown of hydrogen peroxide by catalase?

Accepted Answer

$$2 \mathrm{H}_2\mathrm{O}_2 \rightarrow 2 \mathrm{H}_2\mathrm{O} + \mathrm{O}_2$$

Question 6

A bacterium is found to secrete gelatinase. What does this indicate about its metabolic capabilities?

Accepted Answer

It can break down gelatin into amino acids for further catabolism.

Question 7

Which of the following best describes the fate of fatty acids during catabolism in bacteria?

Accepted Answer

They are broken down by beta-oxidation into acetyl-CoA, which enters the Krebs cycle.

Question 8

Which of the following statements about anabolic reactions is correct?

Accepted Answer

They require energy input (ATP) and use NADPH as a reducing power.

Question 9

Which metabolic pathway is considered amphibolic, functioning in both catabolism and anabolism?

Accepted Answer

Glycolysis

Question 10

A bacterium is positive for the methyl red test. What does this indicate about its metabolism?

Accepted Answer

It performs mixed acid fermentation, producing acidic end products that lower the pH.

Question 11

Which of the following best describes the difference between autotrophs and heterotrophs?

Accepted Answer

Autotrophs fix carbon from inorganic sources, while heterotrophs require organic carbon.

Question 12

Which of the following is a correct pairing of a metabolic test and the enzyme it detects?

Accepted Answer

Catalase test – catalase

Question 13

Which of the following is a correct equation for the net ATP yield from glycolysis alone?

Accepted Answer

$$	ext{Glucose} + 2 	ext{ADP} + 2 	ext{P}_i + 2 	ext{NAD}^+ ightarrow 2 	ext{Pyruvate} + 2 	ext{ATP} + 2 	ext{NADH} + 2 	ext{H}_2	ext{O}$$

Question 14

Which of the following best explains why nucleic acids are not a key dietary energy source for most organisms?

Accepted Answer

Organisms usually salvage nucleotides rather than catabolize them for energy.

Question 15

Which of the following is a real-world application of using metabolic properties to identify bacteria?

Accepted Answer

Using the catalase test to distinguish Staphylococcus (catalase positive) from Streptococcus (catalase negative).

Question 16

Which of the following statements about enzyme regulation in metabolism is correct?

Accepted Answer

Enzyme activity can be regulated by feedback inhibition, allosteric activation/inhibition, and phosphorylation.

Question 17

Which of the following best describes the role of NADPH in cellular metabolism?

Accepted Answer

It provides reducing power for anabolic (biosynthetic) reactions.

Question 18

Which of the following is a correct description of the MacConkey agar test?

Accepted Answer

It is a selective and differential medium that isolates Gram-negative enteric bacteria and differentiates them based on lactose fermentation.

Question 19

Which of the following best describes the process of gluconeogenesis?

Accepted Answer

The synthesis of glucose from non-sugar starting materials.

Microbial Metabolism: Catabolic and Anabolic Pathways, Metabolic Diversity, and Biochemical Identification

Study Guide - Practice Questions