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Free download in PDF DNA Multiple Choice Questions & Answers for competitive exams. These objective type questions are very important for competitive exams like NEET, AIIMS, JIPMER etc. These short solved questions or quizzes are provided by Gkseries.
(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)
DNA is present in
[A]
nucleus only
[B]
nucleus, mitochondria and ER
[C]
nucleus, mitochondria and choloroplast
[D]
nucleus, mitochondria and RER
Answer: nucleus, mitochondria and choloroplast
(3)
Chromatin is composed of
[A]
nucleic acids and protein
[B]
nucleic acids only
[C]
proteins only
[D]
none of these
Answer: nucleic acids and protein
(4)
Adjacent nucleotides are joined by
[A]
covalent bond
[B]
phosphodiester bond
[C]
ionic bond
[D]
peptide bond
Answer: phosphodiester bond
(5)
The type of sugar in DNA are
[A]
triose
[B]
tetrose
[C]
pentose
[D]
hexose
(6)
The length of DNA having 23 base pairs is
[A]
78 Ao
[B]
78.4 Ao
[C]
78.2 Ao
[D]
74.8 Ao
(7)
Z-DNA have a
[A]
Double helical nature
[B]
Zig-Zag apperarance
[C]
uracil base
[D]
single stranded nature
Answer: Zig-Zag apperarance
(8)
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
(9)
The first X-ray diffraction patterns of DNA were taken in 1938 by ___________
[A]
William Asbury
[B]
Rosalind Franklin
[C]
Francis H. Crick
[D]
Linus Pauling
(10)
In 1952, an unambiguous established work in the laboratory of Alexander Todd led to the discovery of _____________
[A]
Chemical nature of DNA
[B]
X-ray diffraction structure of DNA
[C]
3’-5’ phosphodiester linkage regularly links the nucleotides of DNA
[D]
Nucleic acid strands are held together by hydrogen bonds
Answer: 3’-5’ phosphodiester linkage regularly links the nucleotides of DNA
(11)
What should be the complementary strand of 3’….ATGGCTTGA….5’?
[A]
3’….TACCGAACT….5’
[B]
5’….TACCGAACT….3’
[C]
3’….TAGGCAAGT….5’
[D]
5’….TAGGCAAGT….3’
Answer: 5’….TACCGAACT….3’
(12)
The hydrogen bonds formed during A and T bonding occurs between C6NH2 of A and _____
[A]
C4O of T
[B]
PO3–
[C]
C6O of A
[D]
C1O of T
(13)
With respect to the importance of hydrogen bonding and DNA double helix stability, which of the following statements is false?
[A]
Favorable tautomeric form of nucleotide bases
[B]
Contributes to the thermodynamic stability
[C]
Decreases the entropy
[D]
Specificity of base pairing
Answer: Decreases the entropy
(14)
In the late 1970s non double helical form of DNA was also suggested but was discarded on the basis of certain factors. Which of the following is not a factor responsible?
[A]
X-ray crystallography
[B]
Nuclein
[C]
Topoisomerase
[D]
Nucleosome core particle
(15)
DNA replication is
[A]
Conservative
[B]
Non-conservative
[C]
Semi-conservative
[D]
None
Answer: Semi-conservative
(16)
Eukaryotes differ from prokaryote in mechanism of DNA replication due to
[A]
Use of DNA primer rather than RNA primer
[B]
Different enzyme for synthesis of lagging and leading strand
[C]
Discontinuous rather than semi-discontinuous replication
[D]
Unidirectional rather than semi-discontinuous replication
Answer: Discontinuous rather than semi-discontinuous replication
(17)
The reaction in DNA replication catalyzed by DNA ligase is
[A]
Addition of new nucleotides to the leading strand
[B]
Addition of new nucleotide to the lagging strand
[C]
Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand
[D]
Base pairing of the template and the newly formed DNA strand
Answer: Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand
(18)
Which of the following enzymes remove supercoiling in replicating DNA ahead of the replication fork?
[A]
DNA polymerases
[B]
Helicases
[C]
Primases
[D]
Topoisomerases
(19)
Which of the following enzymes is the principal replication enzyme in E. coli?
[A]
DNA polymerase I
[B]
DNA polymerase II
[C]
DNA polymerase III
[D]
None of these
Answer: DNA polymerase III
(20)
Both strands of DNA serve as templates concurrently in
[A]
replication
[B]
excision repair
[C]
mismatch repair
[D]
none of these
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