Question 1

Which enzyme catalyzes the first step of glycolysis, and what is the product of this reaction?

Accepted Answer

Hexokinase; glucose 6-phosphate

Question 2

What is the net ATP yield from the complete aerobic catabolism of one molecule of glucose?

Accepted Answer

$$32\ \mathrm{ATP}$$

Question 3

Which of the following best describes the fate of pyruvate under anaerobic conditions in human muscle cells?

Accepted Answer

It is reduced to lactate

Question 4

Which hormone is released when blood glucose concentration drops, and what is its primary effect on the liver?

Accepted Answer

Glucagon; stimulates glycogen breakdown

Question 5

During the digestion of dietary carbohydrates, which enzyme is responsible for the initial breakdown in the mouth?

Accepted Answer

Salivary $$ \alpha -$$amylase

Question 6

Which pathway is activated when a cell’s need for NADPH or ribose-5-phosphate exceeds its need for ATP?

Accepted Answer

Pentose phosphate pathway

Question 7

Which of the following is a correct summary equation for glycolysis?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 2\ \mathrm{NAD}^+ + 2\ \mathrm{ADP} + 2\ \mathrm{HOPO}_3$$^{2-}$$ \rightarrow 2\ \mathrm{CH}_3\mathrm{COCO}_2^- + 2\ \mathrm{NADH} + 2\ \mathrm{ATP} + 2\ \mathrm{H}_2\mathrm{O} + 2\ \mathrm{H}^+$$

Question 8

Which of the following dietary monosaccharides is converted to glucose 6-phosphate by a five-step pathway before entering glycolysis?

Accepted Answer

D-Galactose

Question 9

What is the primary fate of acetyl-CoA when the citric acid cycle cannot process all of it due to low carbohydrate availability?

Accepted Answer

It is converted to ketone bodies

Question 10

Which of the following statements best explains why 1 gram of fat produces more ATP than 1 gram of glucose?

Accepted Answer

Fatty acids are more reduced and yield more acetyl-CoA per gram

Question 11

Which enzyme catalyzes the cleavage of fructose 1,6-bisphosphate into two three-carbon molecules during glycolysis?

Accepted Answer

Aldolase

Question 12

In the β-oxidation of fatty acids, what is the immediate product after the first oxidation step catalyzed by acyl-CoA dehydrogenase?

Accepted Answer

A fatty acyl-CoA with a trans double bond between the α and β carbons

Question 13

Which of the following is NOT a possible fate of the carbon skeleton of an amino acid after removal of its amino group?

Accepted Answer

Conversion to NADH

Question 14

Which process describes the synthesis of glucose from noncarbohydrate sources such as lactate, amino acids, or glycerol?

Accepted Answer

Gluconeogenesis

Question 15

What is the main function of the Cori Cycle in human metabolism?

Accepted Answer

To recycle lactate produced in muscles back to glucose in the liver

Question 16

Which of the following best describes the role of insulin in blood glucose regulation?

Accepted Answer

It increases glucose uptake and glycogen synthesis

Question 17

Which of the following is a correct equation for the aerobic conversion of pyruvate to acetyl-CoA?

Accepted Answer

$$\mathrm{CH}_3\mathrm{COCO}_2^- + \mathrm{HS{-}CoA} + \mathrm{NAD}^+ \rightarrow \mathrm{CH}_3\mathrm{COSCoA} + \mathrm{CO}_2 + \mathrm{NADH} + \mathrm{H}^+$$

Question 18

Which of the following statements about essential and nonessential amino acids is correct?

Accepted Answer

Essential amino acids must be obtained from the diet

Question 19

Which of the following is a product of the β-oxidation of an 18-carbon fatty acid (stearic acid)?

Accepted Answer

9 Acetyl-CoA, 8 NADH, and 8 FADH$$_2$$

Carbohydrate, Lipid, and Protein Metabolism: Pathways and Regulation

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