Spectrum Biology - September 2016

9. What is the amino acid sequence encoded by

the base sequence : UCA UUU UCC GGG

AGU of a mRNA segment?

(a) Methionine–Phenylalanine–Serine–Glycine–Serine

(b) Glycine–Serine–Phenylalanine–Serine–Glycine

(c) Serine–Phenylalanine–Serine–Glycine–Serine

(d) Serine–Phenylalanine–Glycine–Serine–Glycine

10.Antiparallel strands of a DNA molecule mean

that

(a)one strand turns anticlockwise

(b) the phosphate groups of two DNA strands at their ends,

share the same position

(c) the phosphate groups at the start of two DNA strands

are in opposite position

(d)one strand turns clockwise

11.In the DNA molecule,

(a)the total amount of purine nucleotides and pyrimidine

nucleotides is not always equal

(b) there are two strands, which run parallel in the 53 ′→ ′

direction

(c) the proportion of adenine in relation to thymine varies

with the organism

(d)there are two strands, which run antiparallel–one in

53 ′→ ′ direction and other in 35 ′→ ′

12.The strand of DNA acting as template for

mRNA transcription is

I. coding strand

II. non-coding strand

III. sense strand

IV. anti-sense strand

The correct answer is

(a) I and II

(b) I and IV

(c) II and IV

(d) I and III

13.In a DNA molecule, the adenine is 15%. What

will be the percentage of guanine in this DNA?

(a) 15% (b) 35%

(c) 70% (d) 30%

14.There are 64 codons in the genetic

dictionary as

(a) there are 3 non-sense codons and 61 sense codons

(b) there are 64 different types of tRNA

(c) there are 64 amino acids to be coded

(d) genetic code has a triplet nature

15.During translation initiation in prokaryotes, a

GTP molecule is needed in

(a)association of 30S, mRNA with formyl-met-tRNA

(b) association of 50S subunit of ribosome with initiation

complex

(c) formation of formyl-met-tRNA

(d)binding of 30S subunits of ribosome with mRNA

16.Match the following Columns.

Column I Column II

A. tRNA 1. Linking of amino acids

B. mRNA 2. Transfer of genetic information

C. rRNA 3. Nucleolar organising region

D. Peptidyl

transferase

4. Transfer of amino acid from
   cytoplasm to ribosome

Codes

AB C D

(a)42 3 1

(b)14 3 2

(c)12 3 4

(d)13 2 4

17.What would happen if in a gene encoding a

polypeptide of 50 amino acids 25th (UAC) is

mutated of UAA?

(a)A polypeptide of 49 amino acids will be formed

(b) A polypeptide of 25 amino acids will be formed

(c) A polypeptide of 24 amino acids will be formed

(d)Two polypeptides of 24 and 25 amino acids will be

formed

18.E. coli about to replicate was placed in a

medium containing radioactive thymidine for

5 minutes. Then, it was made to replicate in a

normal medium. Which of the following

observations will be correct?

(a) Both the strands of DNA will be radioactive

(b) One strand radioactive

(c) Each half strand radioactive

(d) None is radioactive

19.Choose the incorrect statement in the process

of protein synthesis.

(a)After uncoiling of DNA molecule, one strand acts as a

template for the formation of mRNA

(b) In the presence of DNA polymerase enzyme, the mRNA

is formed based on the triplet codes

(c) The mRNA that leaves nucleus reaches cytoplasm and

gets attached with 30 S ribosomal subunit

(d)The amino acids are transferred from the intracellular

amino acid pool to the active ribosomes by the tRNA

20.Which of the following is not relevant to the

structure of double helical DNA?

(a)The helix makes one complete spiral turn every 34 Å

(b) The diameter of the helix is 20 Å

(c) The distance between adjacent nucleotide is 3.4 Å

(d)Each strand of helix has a backbone made up of

alternating ribose sugar and phosphate

21.Operon concept was proposed by

(a) Jacob and Monod

(b) David Baltimore

(c) Alec Jeffrey

(d) None of the above