Question 1

Which of the following best describes the relationship between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways degrade macromolecules to release energy, which is then used by anabolic pathways to synthesize macromolecules.

Question 2

Which cofactor is primarily used as a reductant in anabolic (biosynthetic) pathways?

Accepted Answer

NADPH

Question 3

During glycolysis, glucose is converted to pyruvate. Which type of reaction is primarily responsible for the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate?

Accepted Answer

Oxidation-reduction

Question 4

Which of the following transformations is NOT possible given that the pyruvate to acetyl-CoA reaction is irreversible?

Accepted Answer

Acetyl-CoA to glucose

Question 5

Which of the following best explains why NADH is primarily used in catabolic pathways?

Accepted Answer

NADH is re-oxidized by the respiratory chain, producing ATP needed for cellular work.

Question 6

Which regulatory mechanism involves the end product of a metabolic pathway inhibiting an early step in the same pathway?

Accepted Answer

Feedback inhibition

Question 7

A patient has a mutation that prevents phosphorylation of a key metabolic enzyme. Which regulatory mechanism is most directly affected?

Accepted Answer

Covalent modification

Question 8

Which of the following reactions represents an oxidation process?

Accepted Answer

$$\mathrm{CH_3CH_2OH \rightarrow CH_3CHO}$$

Question 9

Which of the following is a key regulatory enzyme in glycolysis that is allosterically regulated and catalyzes a step with a large negative $$\Delta G$$?

Accepted Answer

Phosphofructokinase

Question 10

Which of the following best describes the role of ATP in metabolism?

Accepted Answer

ATP is hydrolyzed to provide energy for anabolic reactions.

Question 11

Which of the following is an example of a phosphate transfer reaction in metabolism?

Accepted Answer

Conversion of glucose to glucose-6-phosphate by hexokinase

Question 12

Which of the following best explains why fatty acid synthesis is considered an anabolic pathway?

Accepted Answer

It requires the input of energy and reducing equivalents to build complex molecules from simpler ones.

Question 13

Which of the following is a consequence of allosteric regulation of a metabolic enzyme?

Accepted Answer

The enzyme's activity is modulated by binding of a molecule at a site other than the active site.

Question 14

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

Accepted Answer

It donates electrons to the respiratory chain, leading to ATP production.

Question 15

Which of the following is an example of regulation by sub-cellular localization?

Accepted Answer

An enzyme is transported from the cytosol to the mitochondria to become active.

Question 16

Which of the following statements about the role of cofactors in metabolism is correct?

Accepted Answer

NAD+ is reduced to NADH during catabolic reactions, which is then oxidized in the respiratory chain.

Question 17

Which of the following best describes the chemical change when pyruvate is converted to acetyl-CoA?

Accepted Answer

Pyruvate is oxidatively decarboxylated, releasing CO$$_2$$ and forming acetyl-CoA.

Question 18

Which of the following is a real-life example of feedback inhibition in metabolism?

Accepted Answer

High levels of ATP inhibit phosphofructokinase in glycolysis.

Question 19

Which of the following best explains why the regulation of metabolic pathways often targets enzymes catalyzing steps with large negative $$\Delta G$$?

Accepted Answer

These steps are essentially irreversible and control the overall flux through the pathway.

Metabolism: Anabolic and Catabolic Pathways, Regulation, and Redox Chemistry

Study Guide - Practice Questions

Study Guide - Flashcards