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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

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 2

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 3

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 4

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 5

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 6

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 7

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


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Question 8


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 9

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 10

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

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

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Question 11

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 12

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 13

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 14

Which of the following is a purine?

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

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Question 15

Which pyrimidine base contains an amino group at carbon 4?

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

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Question 16

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 17

DNA is a polynucleotide.

A. True
B. False

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Question 18

Identify the complementary strand of the DNA primary structure ATGCCGATC.


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Question 19

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 20

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 21

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 22

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 23

Which of the following bases contain two keto groups?

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

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Question 24

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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Question 25

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 26

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 27

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 28

ATP and GTP are __________

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

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Question 29

How many types of nucleotides are present in DNA?

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

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Question 30

Purines and pyrimidines are different molecules.

A. True
B. False

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Question 31

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 32

Which monomers compose the strands of nucleic acids?

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

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Question 33

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 34

Deoxyribose sugar is found in DNA.

A. True
B. False

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Question 35

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 36

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 37

The monomeric unit of nucleic acid are called ___________

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

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Question 38

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 39

What is the energy currency of the living cell?


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Question 40

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 41

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 42

Who discovered nucleic acid?

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

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