Molecular Basis of Inheritance Questions — NEET Biology

Q1

In a DNA, percentage of thymine is 20% then what will be the percentage of guanine?

A 20%

B 40%

C 30%

D 60%

Correct Answer

Option C

Solution

(c) By Chargaff's rule: T=20%, A=20%, so C+G=60%, G=30%.

Q2

During DNA replication, Okazaki fragments are used to elongate:

A The lagging strand towards replication fork.

B The leading strand away from replication fork.

C The lagging strand away from the replication fork.

D The leading strand towards replication fork.

Correct Answer

Option C

Solution

(c) Two DNA polymerase molecules simultaneously work at the DNA fork, one on the leading strand and the other on the lagging strand.

DNA polymerase synthesizes each Okazaki fragment at lagging strand in $5^{\prime}-3^{\prime}$ direction.

Q3

The experimental proof for semiconservative replication of DNA was first shown in a

A Fungus

B Bacterium

C Virus

D Plant

Correct Answer

Option B

Solution

(b) Meselson and Stahl demonstrated semi-conservative replication in the bacterium E. coli.

Q4

Non-membranous nucleoplasmic structures in nucleus are the site for active synthesis of

A tRNA

B protein synthesis

C mRNA

D rRNA

Correct Answer

Option D

Solution

(d) Nucleolus is non-membranous nucleoplasmic structure in nucleus.

Nucleolus is the site of ribosomal RNA (rRNA) synthesis.

Q5

DNA fragments are:

A Negatively charged

B Neutral

C Either positively or negatively charged depending on their size

D Positively charged

Correct Answer

Option A

Solution

(a) DNA fragments are negatively charged due to phosphate groups.

Q6

A nucleotide is formed of

A purine, pyrimidine and phosphate

B purine, sugar and phosphate

C nitrogen base, sugar and phosphate

D pyrimidine, sugar and phosphate

Correct Answer

Option C

Solution

(c) Nucleotide = nitrogenous base + pentose sugar + phosphate group.

Q7

Nucleosome core is made of histone proteins

A H1, H2A, H2B and H3

B H1, H2A, H2B, H4

C H1, H2A, H2B, H3 and H4

D H2A, H2B, H3 and H4

Correct Answer

Option D

Solution

(d) Nucleosome core octamer = H2A, H2B, H3 and H4 (2 copies each); H1 seals the nucleosome.

Q8

Which one of the following is the starter codon?

A AUG

B UGA

C UAA

D UAG

Correct Answer

Option A

Solution

(a) AUG is the start codon coding for methionine.

Q9

The final proof for DNA as the genetic material came from the experiments of:

A Hershey and Chase

B Avery, MacLeod and McCarty

C Hargobind Khorana

D Griffith

Correct Answer

Option A

Solution

(a) Hershey and Chase provided final proof that DNA is the genetic material using bacteriophage.

Q10

What base is responsible for hot spots for spontaneous point mutations?

A Adenine

B 5-bromouracil

C 5-methylcytosine

D Guanine

Correct Answer

Option C

Solution

(c) 5-methylcytosine residues are hotspots for spontaneous transition mutations (C→T).