Q: Which of the following is the correct equation for the conversion of pyruvate to lactate during anaerobic glycolysis?

$$\text{pyruvate} + \text{NADH} + \text{H}^+ \rightarrow \text{NAD}^+ + \text{lactate}$$

Question 1

Which enzyme is responsible for the phosphorylation of glucose to glucose-6-phosphate in the liver, and what is a key regulatory difference compared to the same reaction in muscle?

Accepted Answer

Glucokinase; it is not inhibited by glucose-6-phosphate in the liver

Question 2

During intense exercise, why does skeletal muscle rely on anaerobic glycolysis, and what is the main biochemical reason for this adaptation?

Accepted Answer

To regenerate NAD$$ ^+ $$ from NADH, allowing glycolysis to continue in low oxygen

Question 3

Which of the following best describes the role of glycogen in the liver?

Accepted Answer

Maintains blood glucose concentration under hormonal control

Question 4

What is the net ATP yield from glycolysis of one molecule of glucose under anaerobic conditions?

Accepted Answer

$$2$$ ATP

Question 5

Which enzyme catalyzes the key regulatory step of glycolysis, and how is it allosterically inhibited?

Accepted Answer

Phosphofructokinase; inhibited by ATP

Question 6

Why can only the liver (and kidney) release free glucose into the blood during glycogen breakdown?

Accepted Answer

Only these tissues have glucose-6-phosphatase

Question 7

Which of the following is the correct equation for the conversion of pyruvate to lactate during anaerobic glycolysis?

Accepted Answer

$$	ext{pyruvate} + 	ext{NADH} + 	ext{H}^+ ightarrow 	ext{NAD}^+ + 	ext{lactate}$$

Question 8

Which two reactions in glycolysis result in direct production of ATP by substrate-level phosphorylation?

Accepted Answer

3-phosphoglycerate kinase and pyruvate kinase

Question 9

What is the main reason red blood cells rely exclusively on glycolysis for ATP production?

Accepted Answer

They lack mitochondria

Question 10

Which of the following best explains why the net yield of ATP from glycolysis is only 2 ATP per glucose molecule?

Accepted Answer

4 ATP are produced, but 2 ATP are used in early steps

Question 11

Which intermediate is the immediate product of the oxidation step in glycolysis catalyzed by glyceraldehyde-3-phosphate dehydrogenase?

Accepted Answer

1,3-Bisphosphoglycerate

Question 12

What is the function of UDP-glucose in glycogen synthesis?

Accepted Answer

It acts as an activated glucose donor for glycogen synthase

Question 13

Which bonds are responsible for the branched structure of glycogen?

Accepted Answer

$$\alpha-1$$,4 and $$\alpha-1$$,6 glycosidic bonds

Question 14

Which hormone stimulates glycogen breakdown in the liver during fasting, and what is the key enzyme activated?

Accepted Answer

Glucagon; glycogen phosphorylase

Question 15

Why is the enzyme pyruvate kinase considered irreversible in glycolysis?

Accepted Answer

It catalyzes a reaction with a large negative $$\Delta G$$

Question 16

Which of the following is NOT a source of glucose for glycolysis?

Accepted Answer

Fatty acid oxidation

Question 17

What is the main function of glycolysis in the brain?

Accepted Answer

To provide ATP, as the brain cannot use fats as fuels

Question 18

Which of the following best describes the Warburg effect observed in tumor cells?

Accepted Answer

Tumor cells preferentially generate energy through anaerobic glycolysis even when oxygen is present

Question 19

Which glycolytic enzyme is present in all tissues except the liver and is inhibited by its product?

Accepted Answer

Hexokinase

Question 20

What is the main advantage of the branched structure of glycogen?

Accepted Answer

It allows rapid release of glucose units from multiple ends

Glucose and Glycogen Metabolism: Glycolysis and Its Regulation

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