Biology Multiple Choice Questions and Answers for Different Competitive Exams

MCQ on Biochemistry - Nucleic acid (DNA)

Watson and Crick proposed the double helical structure of DNA
1.  A nucleoside is composed of
a) a base+ a sugar
b) a base+ a sugar+ phosphate
c) a base+ a phosphate
d) none of these

2. Genetic mutation occurs in
a) Protein
b) RNA
c) DNA
d) Nucleus

3. DNA is present in
a) nucleus only
b) nucleus, mitochondria and ER
c) nucleus, mitochondria and choloroplast
d) nucleus, mitochondria and RER

4. DNA is the genetic material in
a) viruses, prokaryote and eukaryote
b) prokaryote and eukaryote
c) only in eukaryotes
d) in some viruses, prokaryotes and eukaryotes

5. The two strands in a DNA double is joined by

a) Co-valent bond
b) Hydrogen bond
c) ionic bond
d) phosphodiester bond

6. Chromatin is composed of
a) nucleic acids and protein
b) nucleic acids only
c) proteins only
d) none of these

7. The basic repeating units of a DNA molecule is
a) nucleoside
b) nucleotide
c) histones
d) aminoacids

8. Adjacent nucleotides are joined by
a) covalent bond
b) phosphodiester bond
c) ionic bond
d) peptide bond

9.  The length of one turn of DNA is
a) 3.4 Ao
b) 34 Ao
c) 20 Ao
d) 3.04 Ao

10.  The type of sugar in DNA are


Nucleotide
a) triose
b) tetrose
c) pentose
d) hexose

11. The width of DNA molecule is
a) 15 Ao
b) 3.4 Ao
c) 20 Ao
d) 25 Ao

12. The length of DNA having 23 base pairs is
a) 78 Ao
b) 78.4 Ao
c) 78.2 Ao
d) 74.8 Ao

13.  Left handed DNA
a) A-DNA
b) B-DNA
c) Z-DNA
d) C-DNA

14.  Z-DNA have a
a) Double helical nature
b) Zig-Zag apperarance
c) uracil base
d) single stranded nature

15. A short length of DNA molecule has 80 thymine and 80 guanine bases. The total number of nucleotide in the DNA fragment is
a) 160
b) 40
c) 320
d) 640

Answers:

1-a
2-c
3-c
4-d
5-b
6-a
7-b
8-b
9-b
10-c
11-c
12-d
13-c
14-b
15-c

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