Molecular Biology and Genetics MCQs

Question 1

Which of the following processes can increase genetic diversity of bacteria in nature? P. Conjugation Q. Transformation R. Transduction S. Transfection

Accepted Answer

P, Q and R only

Answer

P only

Answer

P and Q only

Answer

P, Q, R and S

Question 2

"Determine the correctness or otherwise of the following Assertion (A) and the Reason (R). Assertion: N-methyl-N'-nitro-N-nitrosoguanidine (NTG) is an effective chemical mutagen. Reason: Mutations induced by NTG mainly are the GC → AT transitions."

Accepted Answer

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

Answer

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

Answer

(A) is true but (R) is false

Answer

(A) is false but (R) is true

Question 3

If a segment of a sense strand of DNA is 5'-ATGGACCAGA-3', then the resulting RNA sequence after transcription is

Accepted Answer

5'-AUGGACCAGA-3'

Answer

5'-AGACCAGGTA-3'

Answer

5'-UCUGGUCCAU-3'

Answer

5'-UACCUGGUCU-3'

Question 4

Which of the following statements with respect to the orientation of the nitrogenous bases to the pentose sugars, and the puckering of the sugar, is correct?

Accepted Answer

Anti, and 2'-endo in B form DNA

Answer

Anti, and 2'-endo in A form DNA

Answer

Syn, and 3'-endo in A form DNA

Answer

Syn, and 3'-endo in B form DNA

Question 5

Of the two diploid species, species I has 36 chromosomes and species II has 28 chromosomes. How many chromosomes would be found in an allotriploid individual?

Accepted Answer

46 or 50

Answer

42 or 54

Answer

74 or 86

Answer

84 or 108

Question 6

Ames test is used to determine

Accepted Answer

Both mutagenicity and carcinogenicity of a chemical

Answer

The mutagenicity of a chemical

Answer

Carcinogenicity of a chemical

Answer

Toxicity of a chemical

Question 7

A mutation in a gene that codes for a polypeptide results in a variant polypeptide that lacks the last three amino acids. What type of mutation is this?

Accepted Answer

Nonsense mutation

Answer

Synonymous mutation

Answer

Missense mutation

Answer

Silent mutation

Question 8

Match the entries in Group I with the entries in Group II. Group I Group II P. RNAse P 1. Polyadenylation Q. RNase H 2. Splicing R. snRNAs 3. Ribozymes S. CstF 4. DNA-RNA hybrids

Accepted Answer

P-3, Q-4, R-2, S-1

Answer

P-4, Q-3, R-2, S-1

Answer

P-3, Q-2, R-1, S-4

Answer

P-2, Q-4, R-1, S-3

Question 9

Topological winding number of a 2.0 kb covalently closed circular DNA was found to be 191 with a writhing number of -4. Hence, its linking number and the number of base pair per turn when the molecule is laid flat on the surface is . . . . . . . . and . . . . . . . ., respectively.

Accepted Answer

187, 10.69

Answer

195, 10.25

Answer

200, 10.00

Answer

187, 10.50