Molecular Basis of Inheritance

NEET Biology · 262 questions · Page 12 of 27 · Click an option or "Show Solution" to reveal answer

Q111

An octamer of 4 histones complexed with DNA forms

A endosome

B nucleosome

C mesosome

D centromere

Correct Answer

Option B

Solution

(b) Nucleosomes are oblate spherical structure having an octamer of four histone proteins (constituting 2 molecules of each type).

Q112

In the genetic dictionary, there are 64 codons and each codon consists of three nucleotides

A 64 codons are to be coded

B 64 types of tRNAs are present in the human genome

C there are 3 stop codons and 61 sense codons

D genetic code is triplet code.

Correct Answer

Option D

Solution

(d) Genetic code is triplet coding for one amino acid in a polypeptide chain.

There are four different types of nucleotides A, U, G, and C.

Since a code is a triplet thus $64(4 \times 4 \times 4)$ distinct triplet of bases determine the 20 amino acids.

But out of 64 , only 61 code for 20 amino acids.

Three codons that do not code for any amino acids are terminator or non sense codons (UAG, UGA and UAA).

Q113

Nucleotide arrangement in DNA can be seen by

A X-ray crystallography

B electron microscope

C ultracentrifuge

D light microscope

Correct Answer

Option A

Solution

(a) X-ray crystallography reveals DNA structure; Watson and Crick used Franklin's X-ray data.

Q114

The process of transfer of genetic information from DNA to RNA/formation of RNA from DNA is

A transversion

B transcription

C translation

D translocation

Correct Answer

Option B

Solution

(b) Central dogma of protein synthesis explains a unidirectional or one way flow of information from DNA to RNA (transcription) and from RNA to polypeptide (translation).

Q115

How many base pairs (bp) are found in the haploid genome of humans?

A 2.9x10^9

B 4x10^8

C 7x10^9

D 3x10^9

Correct Answer

Option D

Solution

(d) Human haploid genome contains approximately 3 x 10^9 base pairs.

Q116

The transfer RNA molecule in 3D appears

A L-shaped

B E-shaped

C Y-shaped

D S-shaped

Correct Answer

Option A

Solution

(a) tRNA has an L-shaped 3D structure (as shown by X-ray crystallography).

Q117

Due to discovery of which of the following in 1980 the evolution was termed as RNA world?

A mRNA, tRNA, rRNA synthesise proteins

B In some virus RNA is the genetic material

C RNA have enzymatic property

D RNA is not found in all cells

Correct Answer

Option C

Solution

Q118

Which scientist experimentally proved that DNA is the sole genetic material in bacteriophage?

A Jacob and Monod

B Beadle and Tatum

C Meselson and Stahl

D Hershey and Chase

Correct Answer

Option D

Solution

(d) Hershey and Chase (1952) used 32P and 35S labeled phages to prove DNA is genetic material.

Q119

Polysome is formed by

A several ribosomes attached to a single mRNA

B many ribosomes attached to a strand of endoplasmic reticulum

C a ribosome with several subunits

D ribosomes attached to each other in a linear arrangement

Correct Answer

Option A

Solution

(a) Polysome = multiple ribosomes translating a single mRNA simultaneously.

Q120

What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA?

A A polypeptide of 25 amino acids will be formed

B A polypeptide of 24 amino acids will be formed

C Two polypeptides of 24 and 25 amino acids will be formed

D A polypeptide of 49 amino acids will be formed

Correct Answer

Option B

Solution

(b) UAA is a stop codon; translation terminates at position 24 (before 25th codon).

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