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Nucleic Acids MCQ Questions & Answers

Nucleic Acids MCQs : This section focuses on the "Nucleic Acids". These Multiple Choice Questions (MCQs) should be practiced to improve the Nucleic Acids skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

A five carbon sugar lacking a hydrogen at the number 2 carbon is found in


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Question 2

Name those purine bases which are commonly found in DNA and RNA?

A. Adenine and guanine
B. Cytosine and thymine
C. Adenine and thymine
D. Cytosine and guanine

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Question 3

The primary structure of DNA and RNA proceeds in which direction?

A. 3’ —–> 5҆’
B. 5’ —–> 3’
C. 4’ —–> 6’
D. 3’ —–> 6’

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Question 4


A. can participate in hydrophobic interactions due to its methyl group
B. is replaced by uracil in RNA
C. normally forms two hydrogen bonds with adenosine
D. all of the above

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Question 5

The unfavourable free energy associated with not satisfying a hydrogen bond after formation of the double helix is approximately

A. 10 kJ/mol
B. 20 kJ/mol
C. 25 kJ/mol
D. 30 kJ/mol

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Question 6

The attachment between the base and sugar in a nucleotide is through ______ bond.

A. hydrogen
B. peptide
C. phosphodiester
D. glycosidic

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Question 7

Deoxyribose sugar is found in DNA.

A. True
B. False

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Question 8

Nucleoside is a pyrimidine or purine base

A. covalently bonded to a sugar
B. ionically bonded to a sugar
C. hydrogen bonded to a sugar
D. none of the above

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Question 9

Which of the following statements is correct?

A. Adenine is a pyrimidine
B. DNA is made of amino acids
C. Nucleosides do not contain phosphorous
D. RNA contains thymine

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Question 10

Which pyrimidine base contains an amino group at carbon 4?

A. Cytosine
B. Thymine
C. Uracil
D. Adenine

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Question 11

Purines and pyrimidines are different molecules.

A. True
B. False

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Question 12

What are the types of nucleic acids are found in living organisms?

A. deoxyribonucleic acid & nucleotide acid
B. deoxyribonucleic acid & ribonucleic acid
C. ribonucleic acid & nucleotide acid
D. ribonucleic acid & nucleoside acid

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Question 13

Which of the following is found on RNA but not DNA?

A. Uracil
B. Deoxyribose
C. Phosphate
D. Adenine

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Question 14

The monomeric unit of nucleic acid are called ___________

A. Nucleotides
B. Nucleosides
C. Pyrimidines
D. Purines

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Question 15

The sugar in RNA is __________ , the sugar in DNA is __________

A. deoxyribose, ribose
B. ribose, deoxyribose
C. ribose, phosphate
D. ribose, uracil

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Question 16

RNA on hydrolysis does not yield which of the following?

A. Amino acid
B. Pentose sugar
C. Nitrogen base
D. Phosphoric acid

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Question 17

Two DNA samples A and B have melting temperatures 305K and 320K respectively. Identify the correct statement based on this information.

A. A and B are complementary strands
B. B has more CG pairs than A
C. A has more CG pairs than B
D. A has more hydrogen bonds than B

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Question 18

Which part of the nucleotide is responsible for the formation of bonds in DNA double helix?

A. Base
B. Sugar
C. Phosphate group
D. Hydroxyl group of sugar

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Question 19

A nucleotide consists of

A. a sugar, a base and a phosphate
B. a sugar and a phosphate
C. paired bases
D. a sugar, a base and three phosphates

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Question 20

Name the pyrimidine base which is found in RNA but not in DNA?

A. Thymine
B. Uracil
C. Adenine
D. Guanine

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Question 21

Which sugar is present in RNA?

A. β-D-ribose
B. β-D-fructose
C. β-D-galactose
D. β-D-2-deoxyribose

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Question 22

Which monomers compose the strands of nucleic acids?

A. Amino acids
B. Ribose
C. Functional groups
D. Nucleotides

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Question 23

Because DNA is a highly charged polyanion, its stability to heat denaturation

A. does not depend on hydrophobic interactions
B. increases with increasing salt
C. is independent of G - C content
D. decreases with increasing salt

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Question 24

Which bond is used to stabilize the double helix of DNA?

A. Hydrophobic bond
B. Hydrogen bond
C. Covalent bond
D. Ionic bond

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Question 25

A purified DNA sample of leaf contains 20.0 mole of guanine. Calculate the approximate percentage of purine residues?

A. 30%
B. 40%
C. 60%
D. 20%

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Question 26

What is the energy currency of the living cell?


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Question 27

The glycosidic bonds in DNA and RNA

A. connect the sugar to the base
B. can be hydrolyzed by OH- ion
C. stabilize Watson-Crick H-bonds
D. are free to rotate over about 180°

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Question 28

Which of the following bases contain two keto groups?

A. Adenine
B. Guanine
C. Thymine
D. Cytosine

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Question 29

Nucleotide bases and aromatic amino acids absorb light respectively at

A. 280 and 260 nm
B. 260 and 280 nm
C. 270 and 280 nm
D. 260 and 270 nm

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Question 30

How many types of nucleotides are present in DNA?

A. 1
B. 2
C. 3
D. 4

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Question 31

ATP and GTP are __________

A. cells
B. receptors
C. nucleotides
D. nucleic acids

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Question 32

Which of these statements are INCORRECT according to chargaff’s rules?

A. The molar ratio of A to T or C to G = 1
B. The sum of purine = sum of pyrimidine
C. The % C+G ≠ % A+T
D. The composition of DNA remains the same in all the species

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Question 33

The most stabilizing force for nucleic acids is

A. hydrogen bonds
B. electrostatic bond
C. Van der Waals
D. conformational entropy

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Question 34

In gel electrophoresis, what fragments will move most quickly through a gel?

A. Large fragments
B. Small fragments
C. Large genome
D. None of these

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Question 35

Identify the complementary strand of the DNA primary structure ATGCCGATC.


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Question 36

DNA is a polynucleotide.

A. True
B. False

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Question 37

Which of the following is a purine?

A. Cytosine
B. Adenine
C. Thymine
D. Uracil

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Question 38

Nucleic acids can be analyzed experimentally by their

A. molecular weight
B. absorption of visible light
C. absorption of uv light
D. none of these

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Question 39

A purine with an amine (NH2) group on the 6th carbon is

A. adenine
B. cytosine
C. thymine
D. guanine

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Question 40

Who discovered nucleic acid?

A. Watson and Crick
B. Griffith
C. Friedrich Miescher
D. Walter Gilbert

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Question 41

Nucleotides are linked together by bonds between 5’ and 2’ carbons of two different pentose sugars.

A. True
B. False

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Question 42

Which of the following best describes cytosine?

A. pyrimidine, present in RNA and DNA
B. pyrimidine, present only in DNA
C. purine, present only in RNA
D. purine, present in RNA and DNA

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