Molecular Biology and Genetics MCQs

Question 1

RNA is very much susceptible to hydrolysis in alkali because

Accepted Answer

its 2'-OH group participate in intramolecular cleavage of phosphodiester backbone

Answer

It contains uracil residues in its structure

Answer

Cleavage occurs in the glycosylic bonds of purine bases

Answer

Cleavage occurs in the glycosylic bonds of pyrimidine bases

Question 2

Rho-dependent and rho-independent transcription termination mechanisms operate in prokaryotes. Rho independent termination mechanism involves

Accepted Answer

No protein factors and only RNA secondary structure and run of 'U's

Answer

Binding of the rho protein upstream of the termination element

Answer

Presence of UGA or UAA stop codons

Answer

Binding of accessory factors at termination signal

Question 3

Determine the correctness or otherwise of the following Assertion (A) and the Reason (R). Assertion: Cytoplasmic male sterility (cms) is invariably due to defect(s) in mitochondrial function. Reason: cms can be overcome by pollinating a fertility restoring (Rf ) plant with pollen from a non cms plant.

Accepted Answer

Both (A) and (R) are true and (R) is the correct reason for (A)

Answer

Both (A) and (R) are true and (R) is not the correct reason for (A)

Answer

(A) is false but (R) is true

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(A) is true but (R) is false

Question 4

Mobile genetic elements present in human genome are P. Long interspersed elements (LINEs) Q. Short interspersed elements (SINEs) R. P elements S. IS elements

Accepted Answer

P, Q

Answer

Q, R

Answer

P, R

Answer

Q, S

Question 5

The direction of shell coiling in the snail Limnaea peregra is a classic example of

Accepted Answer

Extra-chromosomal inheritance

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Chromosomal inheritance

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Chromosomal translocation

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Homologous recombination

Question 6

Which of the following characteristics with respect to bacterial DNA polymerase III are true? P. Initiation of chain synthesis Q. 5' → 3' polymerization R. 3' → 5' exonuclease activity S. 5' → 3' exonuclease activity

Accepted Answer

Q and R only

Answer

P and Q only

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Q and S only

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P and S only

Question 7

The protein in eukaryotes which is subjected to degradation undergoes

Accepted Answer

Ubiquitation

Answer

Phosphorylation

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Carboxylation

Answer

Methylation

Question 8

In mismatch correction repair, the parental DNA strand is distinguished from the daughter strand by

Accepted Answer

Methylation

Answer

Acetylation

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Phosphorylation

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Glycosylation

Question 9

Which one of the following is coded by the ABO blood group locus in the human genome?

Accepted Answer

Galactosyltransferase

Answer

Acyl transferase

Answer

Transposase

Answer

β-Galactosidase