Biochemistry - MCQ Practice Questions

Which of the following is true regarding enzyme specificity?

What is the physiological significance of the Cori cycle?

A student observes that an enzyme shows sigmoidal kinetics instead of Michaelis-Menten kinetics. What does this indicate?

How does the proteasome recognize proteins marked for degradation in the ubiquitin-proteasome system?

A mutation changes a hydrophobic valine residue to a charged aspartate in the hydrophobic core of a globular protein. What is the most likely consequence?

A protein exhibits a β-sheet structure rich in proline residues. Why is this structurally problematic?

Which scenario best describes non-competitive enzyme inhibition kinetically?

A patient with galactosemia has a deficiency in which enzyme?

Pasteur effect refers to the inhibition of glycolysis by oxidative phosphorylation. In terms of ATP and citrate, which statement is correct?

In glycolysis, which step is irreversible under physiological conditions and requires a different enzyme during gluconeogenesis?

The Warburg effect describes increased glycolysis in cancer cells even in the presence of oxygen. Which enzyme is typically upregulated in cancer cells to support this?

A 6-month-old infant develops hypoglycemia, hepatomegaly, and lactic acidosis after feeding. Genetic testing reveals glucose-6-phosphatase deficiency (Type I Glycogen Storage Disease). Why does this cause lactic acidosis?

A competitive athlete is found to have a deficiency in muscle phosphorylase (McArdle disease). During intense exercise, which metabolic consequence is PRIMARY?

A patient with hemoglobin C disease (defect in β-globin) shows increased levels of fetal hemoglobin (HbF). Why might elevated HbF reduce hemolysis compared to HbS?

A 3-year-old child presents with hepatomegaly, growth retardation, and elevated liver transaminases. Enzyme assay shows deficiency of lysosomal acid glucosidase (Pompe disease/GSD Type II). Which carbohydrate accumulates PRIMARILY in lysosomes?

Which of the following correctly pairs a glycogen storage disease with its enzyme defect and primary organ affected?

Which monosaccharide cannot be directly metabolized by red blood cells due to lack of specific enzymes?

In the Pasteur effect, the inhibition of glycolysis by oxidative phosphorylation is primarily mediated by which molecule(s)?

A newborn presents with jaundice, hepatomegaly, and infantile cataracts. Laboratory findings show elevated galactose in blood and urine. Which enzyme deficiency is most likely?

A 45-year-old male presents with chronic hyperuricemia and gout. Testing reveals elevated lactic acid and hepatomegaly. Which GSD is most likely?