Question 1

Which of the following statements best explains why glycolysis is considered an ancient and universal metabolic pathway?

Accepted Answer

It occurs in the cytoplasm and does not require specialized organelles or oxygen.

Question 2

During strenuous exercise, muscle cells often switch to lactic acid fermentation. What is the primary reason for this metabolic shift?

Accepted Answer

To regenerate NAD+ so glycolysis can continue in the absence of sufficient oxygen.

Question 3

Which enzyme catalyzes the first committed and highly regulated step of glycolysis, and what is its main allosteric inhibitor?

Accepted Answer

Phosphofructokinase-1 (PFK-1); inhibited by ATP

Question 4

What is the net ATP and NADH yield from glycolysis per molecule of glucose?

Accepted Answer

$$2$$ ATP and $$2$$ NADH

Question 5

Which of the following best describes the fate of pyruvate under anaerobic conditions in yeast?

Accepted Answer

It is converted to ethanol and carbon dioxide.

Question 6

Why are three steps of glycolysis considered irreversible and require bypass reactions in gluconeogenesis?

Accepted Answer

They are highly exergonic and thermodynamically difficult to reverse.

Question 7

Which of the following is a key regulatory mechanism that prevents futile cycling between glycolysis and gluconeogenesis?

Accepted Answer

Reciprocal regulation by allosteric effectors such as AMP and acetyl-CoA.

Question 8

A patient is injected with fluorodeoxyglucose for a PET scan. Why does this compound accumulate in cancer cells?

Accepted Answer

Cancer cells consume glucose rapidly through aerobic glycolysis.

Question 9

Which of the following best explains why glycolysis can proceed in the absence of oxygen?

Accepted Answer

It occurs entirely in the cytosol and does not depend on the electron transport chain.

Question 10

Which of the following alternative substrates can enter the glycolytic pathway after conversion to dihydroxyacetone phosphate?

Accepted Answer

Glycerol

Question 11

What is the main purpose of fermentation in cells under anaerobic conditions?

Accepted Answer

To regenerate NAD+ so glycolysis can continue.

Question 12

Which of the following statements about the energy yield of fermentation is correct?

Accepted Answer

Fermentation yields about 30% efficiency in ATP conservation from glucose.

Question 13

Which enzyme is responsible for the conversion of pyruvate to lactate in muscle cells?

Accepted Answer

Lactate dehydrogenase

Question 14

Which of the following best describes the Cori cycle?

Accepted Answer

The conversion of glucose to lactate in muscle and lactate to glucose in the liver.

Question 15

Which of the following is NOT a direct product of glycolysis?

Accepted Answer

Acetyl-CoA

Question 16

Which of the following best explains why the phosphorylation of glucose by hexokinase is essentially irreversible?

Accepted Answer

ATP hydrolysis provides a large negative $$\Delta G$$, making the reaction exergonic.

Question 17

Which of the following statements about the regulation of glycolysis is correct?

Accepted Answer

AMP activates glycolysis and inhibits gluconeogenesis.

Question 18

Which of the following best describes the energy profile of glycolysis as shown in the energy diagram?

Accepted Answer

The pathway is highly exergonic in the direction of pyruvate formation.

Question 19

Which of the following statements about the fate of NADH produced in glycolysis is correct?

Accepted Answer

Under anaerobic conditions, NADH is used to reduce pyruvate to regenerate NAD+.

Question 20

Which of the following best explains why cancer cells often rely on aerobic glycolysis (the Warburg effect)?

Accepted Answer

To provide biosynthetic precursors for rapid cell proliferation.

Glycolysis and Fermentation: Pathways, Regulation, and Cellular Context

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