Mock Test Set- 12

 

Mock Test Set- 12

Q1. Which antidote is used in cyanide poisoning cases to induce methemoglobinemia?

A. Sodium thiosulfate

B. Sodium nitrite

C. Dimercaprol

D. Atropine

Answer: B. Sodium nitrite

Explanation: Sodium nitrite converts hemoglobin to methemoglobin, which binds cyanide more strongly than cytochrome c oxidase, reducing its toxic effects.

Q2. Which of the following poisons acts as an uncoupler of oxidative phosphorylation?

A. Carbon monoxide

B. Sodium cyanide

C. Dinitrophenol (DNP)

D. Atropine

Answer: C. Dinitrophenol (DNP)

Explanation: DNP uncouples oxidative phosphorylation by dissipating the proton gradient across the mitochondrial membrane, leading to energy loss as heat.

Q3. What is the primary mechanism of action of cyanide toxicity?

A. Disruption of neurotransmitter synthesis

B. Inhibition of cytochrome c oxidase in mitochondria

C. Competitive inhibition of hemoglobin oxygen binding

D. Accumulation of lactic acid

Answer: B. Inhibition of cytochrome c oxidase in mitochondria

Explanation: Cyanide binds to cytochrome c oxidase, halting cellular respiration by inhibiting the electron transport chain, leading to hypoxia at the cellular level.

Q4. Which of the following is a characteristic of organophosphate poisoning?

A. Central nervous system depression

B. Mydriasis and dry skin

C. Bradycardia and excessive salivation

D. Hyperglycemia

Answer: C. Bradycardia and excessive salivation

Explanation: Organophosphates inhibit acetylcholinesterase, causing an accumulation of acetylcholine at synapses, leading to symptoms such as bradycardia, excessive salivation, and miosis (cholinergic effects).

Q5. Which statistical value represents the strength of DNA evidence in court?

A. P-value

B. Random Match Probability (RMP)

C. Allelic frequency

D. Genetic distance

Answer: B. Random Match Probability (RMP)

Explanation: RMP quantifies the likelihood that a randomly selected individual matches a given DNA profile, indicating the evidence's weight.

Q6. What is the approximate size of the human mitochondrial genome?

A. 3,000 bp

B. 16,500 bp

C. 35,000 bp

D. 1 million bp

Answer: B. 16,500 bp

Explanation: The human mitochondrial genome is approximately 16,569 base pairs in size.

Q7. What is the purpose of using DTT (Dithiothreitol) in DNA extraction from semen?

A. To digest proteins

B. To break disulfide bonds in sperm heads

C. To remove cellular debris

D. To denature DNA

Answer: B. To break disulfide bonds in sperm heads

Explanation: DTT breaks disulfide bonds in the sperm head, releasing DNA for analysis.

Q8. What is the role of Mg²⁺ in a PCR reaction?

A. Acts as a cofactor for DNA polymerase

B. Increases primer annealing

C. Inhibits DNA degradation

D. Enhances denaturation

Answer: A. Acts as a cofactor for DNA polymerase

Explanation: Magnesium ions are essential for the enzymatic activity of DNA polymerase during PCR.

Q9. Which type of DNA damage is specifically repaired by photoreactivation?

A. Single-strand breaks

B. Double-strand breaks

C. Thymine dimers

D. Depurination

Answer: C. Thymine dimers

Explanation: Photoreactivation repairs UV-induced thymine dimers using photolyase and light energy.

Q10. Which mutation type would most likely result in a frameshift?

A. Transition mutation

B. Transversion mutation

C. Insertion of one nucleotide

D. Missense mutation

Answer: C. Insertion of one nucleotide

Explanation: Insertions or deletions that are not multiples of three nucleotides cause frameshift mutations, altering the reading frame of the genetic code.

Author:- Srishti Dutta