Q: Which of the following is the correct overall equation for glycolysis?

$\text{Glucose} + 2\text{ADP} + 2\text{P}_i + 2\text{NAD}^+ \rightarrow 2\text{Pyruvate} + 2\text{ATP} + 2\text{NADH} + 2\text{H}^+ + 2\text{H}_2\text{O}$

Question 1

Which of the following best describes the main purpose of glycolysis in cellular metabolism?

Accepted Answer

To split glucose into two molecules of pyruvate, generating ATP and NADH

Question 2

Which enzyme catalyzes the phosphorylation of glucose to glucose-6-phosphate in most tissues, and what is a key regulatory feature of this enzyme?

Accepted Answer

Hexokinase; allosterically inhibited by glucose-6-phosphate

Question 3

During strenuous anaerobic exercise, why is lactate produced in muscle cells?

Accepted Answer

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

Question 4

Which of the following is the correct overall equation for glycolysis?

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{H}_2	ext{O}$

Question 5

Which enzyme is responsible for the irreversible conversion of phosphoenolpyruvate (PEP) to pyruvate, and what is a key requirement for its activity?

Accepted Answer

Pyruvate kinase; requires Mg$^{2+}$ and K$^+$

Question 6

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

Accepted Answer

Phosphofructokinase-1 is a key regulatory enzyme, activated by AMP and inhibited by ATP

Question 7

A patient is exposed to fluoride, which inhibits enolase. What is the most likely metabolic consequence?

Accepted Answer

Accumulation of 2-phosphoglycerate and decreased ATP production

Question 8

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

Accepted Answer

It occurs in the cytosol and does not require oxygen, allowing early life to generate energy anaerobically

Question 9

Which of the following is a direct product of the pyruvate dehydrogenase complex reaction?

Accepted Answer

Acetyl-CoA, NADH, and CO$_2$

Question 10

Which of the following best describes substrate-level phosphorylation in glycolysis?

Accepted Answer

The direct transfer of a phosphate group from a high-energy substrate to ADP, forming ATP

Question 11

Which of the following statements about the fate of pyruvate in animal cells is NOT true?

Accepted Answer

Pyruvate is decarboxylated to acetaldehyde, which is then reduced to ethanol

Question 12

Which hormone stimulates the activity of both hexokinase and glucokinase, and what is the effect?

Accepted Answer

Insulin; increases conversion of glucose to glucose-6-phosphate

Question 13

Which of the following best explains why glycolysis is the only source of energy in erythrocytes?

Accepted Answer

Erythrocytes lack mitochondria and cannot perform oxidative phosphorylation

Question 14

Which of the following is a consequence of iodoacetate inhibition in glycolysis?

Accepted Answer

Inhibition of glyceraldehyde-3-phosphate dehydrogenase, blocking ATP and NADH production

Question 15

A patient is fasting for an extended period. Which enzyme is upregulated to favor fat utilization and reduce glucose oxidation?

Accepted Answer

Pyruvate dehydrogenase kinase (PDK)

Question 16

Which of the following best describes the effect of a high-fat diet on pyruvate dehydrogenase complex (PDC) activity in muscle?

Accepted Answer

It lowers PDC activity, favoring fat oxidation over carbohydrate oxidation

Question 17

Which of the following is a key difference between hexokinase and glucokinase?

Accepted Answer

Hexokinase is present in most tissues and has a low $K_m$ for glucose, while glucokinase is liver-specific and has a high $K_m$

Question 18

Which glycolytic enzyme catalyzes the first reaction that yields NADH?

Accepted Answer

Glyceraldehyde-3-phosphate dehydrogenase

Question 19

Which of the following best describes the role of the pyruvate dehydrogenase complex in metabolism?

Accepted Answer

It links glycolysis to the citric acid cycle by converting pyruvate to acetyl-CoA

Glycolysis & Pyruvate Dehydrogenase Complex: Biochemical Pathways and Regulation

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