Question 1

Which of the following molecules is the primary product of glycolysis under anaerobic conditions in human muscle cells?

Accepted Answer

Lactate

Question 2

A patient presents with muscle cramps during intense exercise. Blood analysis shows elevated lactate levels. Which metabolic pathway is most likely upregulated?

Accepted Answer

Anaerobic glycolysis

Question 3

Which enzyme catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate in glycolysis?

Accepted Answer

Phosphoglucose isomerase

Question 4

During gluconeogenesis, which enzyme bypasses the irreversible step catalyzed by phosphofructokinase-1 in glycolysis?

Accepted Answer

Fructose-1,6-bisphosphatase

Question 5

A Lineweaver–Burk plot for an enzyme in the presence of a competitive inhibitor will show:

Accepted Answer

Same y-intercept, different slopes

Question 6

If the slope of a Lineweaver–Burk plot is $$0.5 \ 	ext{min}/\mu	ext{M}$$ and the y-intercept is $$0.1 \ 	ext{min}/\mu	ext{mol}$$, what is $$K_m$$? (Hint: slope = $$K_m/V_{max}$$, intercept = $$1/V_{max})$$

Accepted Answer

$$2 \ \mu	ext{M}$$

Question 7

Which of the following statements best describes uncompetitive inhibition?

Accepted Answer

Inhibitor binds only to the enzyme-substrate complex

Question 8

Which lipid is made of glycerol + 3 fatty acid chains and primarily functions in long-term energy storage?

Accepted Answer

Triacylglycerol

Question 9

Which molecule is the precursor ('seed') for all steroid hormones?

Accepted Answer

Cholesterol

Question 10

Which of the following is NOT a steroid hormone?

Accepted Answer

Thyroxine (T4)

Question 11

Which pathway is inhibited when glucagon levels rise?

Accepted Answer

Glycolysis

Question 12

Which cell type depends exclusively on glycolysis for ATP production?

Accepted Answer

Red blood cells

Question 13

Which enzyme catalyzes the breakdown of peptide bonds by the addition of water molecules during protein digestion?

Accepted Answer

Hydrolases

Question 14

Which of the following is NOT a form of passive transport across cell membranes?

Accepted Answer

Symport (carrier-mediated)

Question 15

A patient with a deficiency in glucose-6-phosphatase would have impaired ability to:

Accepted Answer

Release free glucose from the liver during fasting

Question 16

Which of the following best describes the effect of a noncompetitive inhibitor on enzyme kinetics?

Accepted Answer

$$K_m$$ unchanged, $$V_{max}$$ decreases

Question 17

Which molecule is the main source of energy for the brain during prolonged fasting ($$\u003e2$$–3 days)?

Accepted Answer

Ketone bodies

Question 18

Which enzyme is responsible for removing branches during glycogenolysis?

Accepted Answer

Debranching enzyme

Question 19

Which of the following is the direct substrate for glycogen synthase?

Accepted Answer

UDP-glucose

Question 20

Which of the following best explains the effect of insulin on glucose metabolism in the fed state?

Accepted Answer

Stimulates glycolysis and glycogen synthesis

Comprehensive Biochemistry Exam Study Guide: Enzymes, Metabolism, and Regulation

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