Mock test 1

Biochemistry Mock Test - 01

Time: 15:00

1. Which of the following is an example of an epimeric pair? A) D-Glucose and L-Glucose B) D-Glucose and D-Galactose C) D-Glucose and D-Fructose D) D-Glucose and D-Ribose

Correct Answer: B. D-Glucose and D-Galactose are C-4 epimers.

2. The buffering capacity of an amino acid is maximum at: A) Its Isoelectric point (pI) B) pH values equal to its pKa C) pH 7.0 D) Neutral pH only

Correct Answer: B. Buffering capacity is maximum when pH = pKa.

3. In non-competitive inhibition, the Vmax and Km changes as: A) Vmax decreases, Km remains constant B) Vmax remains constant, Km increases C) Both Vmax and Km decrease D) Both Vmax and Km increase

Correct Answer: A. Non-competitive inhibitors reduce Vmax but do not affect the affinity (Km).

4. Which of the following vitamins is a precursor for FAD? A) Niacin (B3) B) Riboflavin (B2) C) Thiamine (B1) D) Pyridoxine (B6)

Correct Answer: B. Riboflavin is the precursor for Flavin Adenine Dinucleotide (FAD).

5. Cyanide inhibits cellular respiration by binding to: A) Complex I B) Complex II C) Cytochrome c oxidase (Complex IV) D) ATP Synthase

Correct Answer: C. Cyanide binds to the Fe3+ in Cytochrome a3 of Complex IV.

6. A double-stranded DNA molecule has 30% Adenine. What is the percentage of Cytosine? A) 30% B) 20% C) 70% D) 40%

Correct Answer: B. By Chargaff's rule: A=T(30+30=60%). G+C must be 40%. Therefore C = 20%.

7. The primary force stabilizing the Alpha-helix is: A) Electrostatic interactions B) Hydrophobic interactions C) Intrachain Hydrogen bonds D) Disulfide bonds

Correct Answer: C. Alpha-helices are stabilized by H-bonds between N-H and C=O of the backbone.

8. Beta-oxidation of fatty acids occurs in the: A) Cytosol B) Mitochondrial Matrix C) Endoplasmic Reticulum D) Golgi Apparatus

Correct Answer: B. While fatty acid synthesis occurs in the cytosol, oxidation occurs in the matrix.

9. Which urea cycle enzyme is located in the mitochondria? A) Arginase B) Argininosuccinate lyase C) Ornithine Transcarbamoylase D) Argininosuccinate synthetase

Correct Answer: C. OTC and CPS-1 are the two mitochondrial enzymes of the urea cycle.

10. 2,4-Dinitrophenol (DNP) acts as: A) ETC Inhibitor B) ATP Synthase Inhibitor C) Uncoupler of Oxidative Phosphorylation D) Allosteric activator of Glycolysis

Correct Answer: C. DNP carries protons across the inner membrane, dissipating the gradient.