Mock test 3

Biochemistry Mock Test - 03

15:00

1. Which of the following is the key regulatory enzyme of Fatty Acid Synthesis? A) Fatty acid synthase B) Acetyl-CoA Carboxylase (ACC) C) Ketoacyl reductase D) Thiolase

Correct: B. ACC catalyzes the rate-limiting step: conversion of Acetyl-CoA to Malonyl-CoA.

2. SDS-PAGE separates proteins primarily based on their: A) Isoelectric point B) Shape C) Molecular Mass D) Charge-to-mass ratio

Correct: C. SDS denatures proteins and gives them a uniform negative charge, making mass the only variable.

3. How many ATP molecules are net produced when one molecule of Glucose is converted to Lactate? A) 2 B) 4 C) 32 D) 38

Correct: A. Anaerobic glycolysis produces a net of 2 ATP.

4. Which of the following amino acids is both Glycogenic and Ketogenic? A) Glycine B) Leucine C) Phenylalanine D) Alanine

Correct: C. Phenylalanine, Tyrosine, Tryptophan, and Isoleucine are both. (Leucine and Lysine are purely ketogenic).

5. The reaction of the TCA cycle that produces GTP/ATP by substrate-level phosphorylation is: A) Isocitrate to alpha-ketoglutarate B) Succinyl-CoA to Succinate C) Succinate to Fumarate D) Malate to Oxaloacetate

Correct: B. Catalyzed by Succinyl-CoA synthetase.

6. Which coenzyme is required for the oxidative decarboxylation of pyruvate? A) Biotin B) Thiamine Pyrophosphate (TPP) C) Pyridoxal Phosphate (PLP) D) Ascorbic acid

Correct: B. TPP is part of the E1 subunit of the Pyruvate Dehydrogenase complex.

7. Edman degradation is used for: A) DNA sequencing B) Protein N-terminal sequencing D) C-terminal identification

Correct: B. It removes one amino acid at a time from the N-terminus.

8. In competitive inhibition, the Lineweaver-Burk plot shows lines that intersect at: A) The X-axis B) The Y-axis C) The origin D) No intersection

Correct: B. Because Vmax remains unchanged (Y-intercept = 1/Vmax).

9. Which lipid is a major component of the inner mitochondrial membrane? A) Cholesterol B) Sphingomyelin C) Cardiolipin D) Phosphatidylcholine

Correct: C. Cardiolipin is essential for the function of the Electron Transport Chain.

10. The effect of 2,3-BPG on Hemoglobin is to: A) Increase O2 affinity B) Decrease O2 affinity C) Bind to the Heme iron D) Stabilize the R-state

Correct: B. 2,3-BPG stabilizes the T-state (Deoxy), helping O2 release in tissues.