CBSE Class 12 Biology Molecular Basis Of Inheritance Minds Map

Important Questions for NCERT Class 12 Biology Molecular Basis of Inheritance

Ques. 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 24 amino acids will be formed.
(b) Two polypeptides of 24 and 25 amino acids will be formed.
(c) A polypeptide of 49 amino acids will be formed.
(d) A polypeptide of 25 amino acids will be formed.

Answer: A

Ques. Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as ‘start’ or ‘stop’ codon ?
(a) UCG – Start (b) UUU – Stop
(c) UGU – Leucine (d) UAC – Tyrosine

Answer: D

Ques. Degeneration of a genetic code is attributed to the
(a) first member of a codon
(b) second member of codon
(c) entire codon
(d) third member of a codon. 

Answer: D

Ques. In the genetic code dictionary, how many codons are used to code for all the 20 essential amino acids ?
(a) 20 (b) 64
(c) 61 (d) 60 

Answer: C

Ques. Out of 64 codons, 61 codons code for 20 types of amino acid. It is called
(a) degeneracy of genetic code
(b) overlapping of gene
(c) wobbling of codon
(d) universility of codons.

Answer: A

Ques. Change in sequence of nucleotide in DNA is called
(a) mutagen (b) mutation
(c) recombination (d) translation. 

Answer: B

Ques. Which of the following is initiation codon?
(a) UAG (b) AUC
(c) AUG (d) CCU 

Answer: C

Ques. Initiation codon in eukaryotes is
(a) GAU (b) AGU
(c) AUG (d) UAG. 

Answer: C

Ques. What base is responsible for hot spots for spontaneous point mutations?
(a) 5-bromouracil (b) 5-methylcytosine
(c) Guanine (d) Adenine 

Answer: C

Ques. The codons causing chain termination are
(a) AGT, TAG, UGA (b) UAG, UGA, UAA
(c) TAG, TAA, TGA (d) GAT, AAT, AGT.

Answer: B

Ques. Which of the following serves as a terminal codon?
(a) UAG (b) AGA
(c) AUG (d) GCG 

Answer: A

Ques. If the DNA codons are ATG ATG ATG and a cytosine base is inserted at the beginning, then which of the following will result?
(a) CAT GAT GAT G (b) A non-sense mutation
(c) C ATG ATG ATG (d) CA TGA TGA TG

Answer: A

Ques. Anticodon is an unpaired triplet of bases in an exposed position of
(a) tRNA (b) mRNA
(c) rRNA (d) both (b) and (c). 

Answer: A

Ques. Initiation codon of protein synthesis (in eukaryotes) is
(a) GUA (b) GCA
(c) CCA (d) AUG. 

Answer: D

Ques. Khorana first deciphered the triplet codons of
(a) serine and isoleucine
(b) cysteine and valine
(c) tyrosine and tryptophan
(d) phenylalanine and methinonine. 

Answer: B

Ques. In the genetic dictionary, there are 64 codons as
(a) 64 amino acids are to be coded
(b) 64 types of tRNAs are present
(c) there are 44 nonsense codons and 20 sense codons
(d) genetic code is triplet. 

Answer: D

Ques. Genetic code consists of
(a) adenine and guanine (b) cytosine and uracil
(c) cytosine and guanine (d) all of these. 

Answer: D

Ques. The first phase of translation is
(a) binding of mRNA to ribosome
(b) recognition of DNA molecule
(c) aminoacylation of tRNA
(d) recognition of an anti-codon. 

Answer: C

Ques. Many ribosomes may associate with a single mRNA to form multiple copies of a polypeptide simultaneously. Such strings of ribosomes are termed as
(a) polysome (b) polyhedral bodies
(c) plastidome (d) nucleosome.

Answer: A

Ques. A complex of ribosomes attached to a single strand of RNA is known as
(a) polypeptide (b) Okazaki fragment
(c) polysome (d) polymer.

Answer: C