Question 1

Which of the following best describes the difference between catabolic and anabolic reactions in cellular metabolism?

Accepted Answer

Catabolic reactions break down larger molecules into smaller ones and release energy, while anabolic reactions build larger molecules from smaller ones and require energy.

Question 2

Which enzyme classification is responsible for transferring electrons or hydrogen atoms from one molecule to another, and what is a typical example?

Accepted Answer

Oxidoreductases; Lactic acid dehydrogenase

Question 3

A scientist observes that an enzyme's activity increases as substrate concentration rises, but then plateaus even as more substrate is added. What is the most likely explanation for this observation?

Accepted Answer

The enzyme has reached its saturation point, where all active sites are occupied.

Question 4

Which of the following is an example of negative feedback in enzyme activity?

Accepted Answer

A product of a metabolic pathway inhibits the first enzyme in the pathway, shutting down further production.

Question 5

Which type of phosphorylation involves the direct transfer of a phosphate group to ADP from another phosphorylated organic compound?

Accepted Answer

Substrate-level phosphorylation

Question 6

A bacterium is grown in a medium containing both glucose and lactose. It only utilizes glucose until it is depleted, then begins to metabolize lactose. Which regulatory mechanism explains this behavior?

Accepted Answer

Catabolite repression, where the presence of glucose suppresses the expression of lactose-utilizing proteins.

Question 7

Which of the following best defines amphilbolic reactions?

Accepted Answer

Reactions that can proceed in either direction—toward catabolism or anabolism.

Question 8

Which enzyme classification catalyzes the joining of two or more chemicals, and what is a typical example?

Accepted Answer

Ligase or polymerase; Acetyl-CoA synthetase

Question 9

Which of the following statements about oxidation and reduction reactions is correct?

Accepted Answer

Oxidation is the loss of electrons or hydrogen atoms, while reduction is the gain of electrons or hydrogen atoms.

Question 10

Which process uses light energy to add inorganic phosphate to ADP, forming ATP?

Accepted Answer

Photophosphorylation

Question 11

Which of the following is a function of hydrolase enzymes?

Accepted Answer

Hydrolysis (catabolic) reactions

Question 12

A patient is suffering from acidosis, which lowers the pH of their blood. How might this affect the activity of enzymes in their body?

Accepted Answer

Enzymes may denature, losing their secondary and tertiary structures, resulting in decreased activity.

Question 13

Which of the following is NOT a way cells regulate metabolism?

Accepted Answer

Direct phosphorylation of DNA to alter metabolic pathways

Question 14

Which of the following is a biosynthetic pathway for carbohydrates in animals?

Accepted Answer

Glycogen synthesis from glucose

Question 15

Which of the following best describes the role of competitive inhibitors in enzyme activity?

Accepted Answer

They bind to the enzyme's active site and prevent substrate binding.

Question 16

Which of the following equations correctly represents the formation of ATP by substrate-level phosphorylation?

Accepted Answer

$$ADP + P_i \rightarrow ATP$$

Question 17

Which of the following is a correct example of an isomerase enzyme and its function?

Accepted Answer

Phosphoglucoisomerase; rearrangement of atoms within a molecule

Question 18

A cell is exposed to a non-competitive inhibitor. What is the most likely effect on enzyme activity?

Accepted Answer

The inhibitor binds to a site other than the active site, altering the enzyme's shape and reducing activity.

Question 19

Which of the following is a correct description of the biosynthesis of amino acids in cells?

Accepted Answer

Amino acids are synthesized from precursor metabolites derived from glycolysis, the citric acid cycle, and the pentose phosphate pathway.

Metabolism, Enzyme Function, and Regulation in Microbiology

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