Molecular Basis of Inheritance — Page 9 | NEET Biology

Q81

The telomeres of eukaryotic chromosomes consist of short sequences of

A thymine rich repeats

B cytosine rich repeats

C adenine rich repeats

D guanine rich repeats

Correct Answer

Option D

Solution

(d) Telomeres are non sticky terminal ends of the chromosomes. It has heterochromatin and repetitive DNA.

Q82

In a mutational event, when adenine is replaced by guanine, it is a case of

A frame shift mutation

B transcription

C transition

D transversion

Correct Answer

Option C

Solution

(c) In transition, a purine is replaced by another purine base (A with G or vice-versa).

In transversion, a purine is replaced by a pyrimidine base or vice-versa.

Q83

Telomerase is an enzyme which is a

A simple protein

B RNA

C ribonucleoprotein

D repetitive DNA

Correct Answer

Option C

Solution

(c) Telomerase is a ribonucleoprotein which synthesises G rich strand of telomeres in DNA.

Q84

Molecular basis of organ differentiation depends on the modulation in transcription by

A ribosome

B transcription factor

C anticodon

D RNA polymerase.

Correct Answer

Option B

Solution

(b) Transcription factors modulate transcription during organ differentiation.

Q85

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 (Polyribosome) is a complex formed by several ribosomes attached to a single mRNA molecule in the process of translation.

Q86

Which one of the following pairs of codons is correctly matched with their function or the signal for the particular amino acid?

A GUU, GCU-Alanine

B UAG, UGA-Stop

C AUG, ACG-Start/Methionine

D UUA, UCA-Leucine

Correct Answer

Option B

Solution

(b) GCU indicates alanine but GUU indicates valine.

Stop codons are UAG, UGA and UAA.

AUG is the most common start codon which codes for methionine.

UUA indicates leucine but UCA indicates serine.

Q87

Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a triplet

A Hershey and Chase

B Morgan and Sturtevant

C Beadle and Tantum

D Nirenberg and Mathaei

Correct Answer

Option D

Solution

(d) Nirenberg and Mathaei (1961) experimentally proved that a single amino acid is determined by a sequence of three nitrogen bases.

The sequence of three nitrogen bases determining a single amino acid is called a triplet code.

Q88

Removal of introns and joining the exons in a defined order in a transcription unit is called:

A tailing

B transformation

C capping

D splicing

Correct Answer

Option D

Solution

(d) Splicing is the removal of introns and joining the exons in a defined order in a transcription unit.

Q89

What is not true for genetic code?

A It is nearly universal

B It is degenerate

C It is unambiguous

D A codon in mRNA is read in a non contiguous fashion

Correct Answer

Option D

Solution

(d) The genetic code consists of 64 triplets of nucleotides.

These triplets are called codons.

With three exceptions, each codon encodes for one of the 20 amino acids used in the synthesis of proteins.

Q90

The one aspect which is not a salient feature of genetic code, is its being:

A degenerate

B ambiguous

C universal

D specific

Correct Answer

Option B

Solution

(b) Genetic code is non-ambiguous.

There is no ambiguity for a particular codon.

A particular codon will always code for the same amino acid, where ever it is found.