Molecular Basis of Inheritance — Page 26 | NEET Biology

Q251

From the following, identify the correct combination of salient features of Genetic Code.

A Degenerate, Non-overlapping, Nonambiguous

B Universal, Non-ambiguous, Overlapping

C Degenerate, Overlapping, Commaless

D Universal, Ambiguous, Degenerate

Correct Answer

Option A

Solution

(a) Genetic code is degenerate, non-overlapping and non-ambiguous (unambiguous).

Q252

The first phase of translation is

A Recognition of the DNA molecule

B Aminoacylation of tRNA

C Recognition of an anti-codon

D Binding of mRNA to ribosome

Correct Answer

Option B

Solution

(b) Aminoacylation (charging) of tRNA is the first phase of translation.

Q253

An octamer of 4 histones complexed with DNA forms

A endosome

B nucleosome

C mesosome

D centromere

Correct Answer

Option B

Solution

(b) Nucleosome: DNA wrapped around an octamer of 4 histones (H2A, H2B, H3, H4).

Q254

In the genetic dictionary, there are 64 codons and each codon consists of three nucleotides. One correct statement is

A 64 codons are to be coded

B 64 types of tRNAs are present

C there are 3 stop codons and 61 sense codons

D genetic code is triplet code.

Correct Answer

Option D

Solution

(d) The genetic code is a triplet code (3 nucleotides per codon); 3 stop + 61 sense codons.

Q255

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

A transversion

B transcription

C translation

D translocation

Correct Answer

Option B

Solution

(b) Transcription is copying genetic information from DNA to RNA.

Q256

Escherichia coli fully labelled with 15N is allowed to grow in 14N medium. The two strands of DNA molecule of the first generation bacteria have

A different density and do not resemble parent DNA

B different density but resemble parent DNA

C same density and resemble parent DNA

D same density but do not resemble parent DNA

Correct Answer

Option C

Solution

(c) After one generation in 14N, hybrid DNA settles at intermediate density — semi-conservative.

Q257

Because most of the amino acids are represented by more than one codon, the genetic code is

A overlapping

B wobbling

C degenerate

D generate

Correct Answer

Option C

Solution

(c) Degeneracy: most amino acids have more than one codon.

Q258

During DNA replication, the strands separate by

A DNA polymerase

B topoisomerase

C unwindase/Helicase

D gyrase

Correct Answer

Option C

Solution

(c) Helicase (unwindase) unwinds and separates DNA strands at the replication fork.

Q259

The process of translation is

A ribosome synthesis

B protein synthesis

C DNA synthesis

D RNA synthesis

Correct Answer

Option B

Solution

(b) Translation is the synthesis of protein from mRNA template at ribosomes.

Q260

The wild type E. coli cells are growing in normal medium with glucose. They are transferred to a medium containing only lactose as sugar. Which of the following changes takes place?

A The lac operon is repressed

B All operons are induced

C The lac operon is induced

D E.coli cells stop dividing

Correct Answer

Option C

Solution

(c) In the presence of lactose (inducer), the lac operon is induced.