Molecular Basis of Inheritance — Page 25 | NEET Biology

Q241

Three codons causing chain termination are

A TAG, TAA, TGA

B GAT, AAT, AGT

C AGT, TAG, UGA

D UAG, UGA, UAA

Correct Answer

Option D

Solution

(d) Stop codons are UAA (ochre), UAG (amber) and UGA (opal).

Q242

Which step of translation does not consume a high energy phosphate bond?

A Translocation

B Amino acid activation

C Peptidyl-transferase reaction

D Aminoacyl tRNA binding to active ribosomal site

Correct Answer

Option C

Solution

(c) Peptidyl transferase reaction (peptide bond formation) does not require ATP/GTP.

Q243

Genes that are involved in turning on or off the transcription of a set of structural genes are called

A Operator genes

B Redundant genes

C Regulator genes

D Polymorphic genes

Correct Answer

Option C

Solution

(c) Regulator genes control expression of structural genes by encoding repressors/activators.

Q244

DNA elements which can switch their position are called

A exons

B introns

C cistrons

D transposons

Correct Answer

Option D

Solution

(d) Transposons (jumping genes) are DNA elements that can move within the genome.

Q245

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 (unambiguous) — each codon codes for exactly one amino acid.

Q246

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

A Looping

B Inducing

C Slicing

D Splicing

Correct Answer

Option D

Solution

(d) Splicing is the removal of introns and joining of exons by spliceosome.

Q247

Which one of the following is not a part of a transcription unit in DNA?

A The inducer

B A terminator

C A promoter

D The structural gene

Correct Answer

Option A

Solution

(a) Transcription unit = promoter + structural gene + terminator. Inducer is not part of it.

Q248

Removal of RNA polymerase III from nucleoplasm will affect the synthesis of:

A tRNA

B hnRNA

C mRNA

D rRNA

Correct Answer

Option A

Solution

(a) RNA polymerase III synthesises tRNA and 5S rRNA in eukaryotes.

Q249

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) Okazaki fragments elongate the lagging strand away from the replication fork.

Q250

If there are 999 bases in an RNA that codes for a protein with 333 amino acids, and the base at position 901 is deleted such that the length of the RNA becomes 998 bases, how many codons will be altered?

A 11

B 33

C 333

D 1

Correct Answer

Option B

Solution

(b) Deletion at position 901 alters the remaining 33 codons (positions 901-999).