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
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
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
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
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
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
Question 7
A five carbon sugar lacking a hydrogen at the number 2 carbon is found in
A. DNA
B. RNA
C. mRNA
D. rDNA
Question 8
Thymidine
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
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
Question 10
Which of the following is found on RNA but not DNA?
A. Uracil
B. Deoxyribose
C. Phosphate
D. Adenine
Question 11
The sugar in RNA is __________ , the sugar in DNA is __________
A. deoxyribose, ribose
B. ribose, deoxyribose
C. ribose, phosphate
D. ribose, uracil
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°
Question 13
A purine with an amine (NH2) group on the 6th carbon is
A. adenine
B. cytosine
C. thymine
D. guanine
Question 14
Which of the following is a purine?
A. Cytosine
B. Adenine
C. Thymine
D. Uracil
Question 15
Which pyrimidine base contains an amino group at carbon 4?
A. Cytosine
B. Thymine
C. Uracil
D. Adenine
Question 16
The most stabilizing force for nucleic acids is
A. hydrogen bonds
B. electrostatic bond
C. Van der Waals
D. conformational entropy
Question 17
DNA is a polynucleotide.
A. True
B. False
Question 18
Identify the complementary strand of the DNA primary structure ATGCCGATC.
A. AUGCCGAUC
B. TACGGCTAG
C. UACGGCUAG
D. GATCGGCAT
Question 19
RNA on hydrolysis does not yield which of the following?
A. Amino acid
B. Pentose sugar
C. Nitrogen base
D. Phosphoric acid
Question 20
The attachment between the base and sugar in a nucleotide is through ______ bond.
A. hydrogen
B. peptide
C. phosphodiester
D. glycosidic
Question 21
Nucleotides are linked together by bonds between 5’ and 2’ carbons of two different pentose sugars.
A. True
B. False
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
Question 23
Which of the following bases contain two keto groups?
A. Adenine
B. Guanine
C. Thymine
D. Cytosine
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
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
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
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
Question 28
ATP and GTP are __________
A. cells
B. receptors
C. nucleotides
D. nucleic acids
Question 29
How many types of nucleotides are present in DNA?
A. 1
B. 2
C. 3
D. 4
Question 30
Purines and pyrimidines are different molecules.
A. True
B. False
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
Question 32
Which monomers compose the strands of nucleic acids?
A. Amino acids
B. Ribose
C. Functional groups
D. Nucleotides
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%
Question 34
Deoxyribose sugar is found in DNA.
A. True
B. False
Question 35
Name the pyrimidine base which is found in RNA but not in DNA?
A. Thymine
B. Uracil
C. Adenine
D. Guanine
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
Question 37
The monomeric unit of nucleic acid are called ___________
A. Nucleotides
B. Nucleosides
C. Pyrimidines
D. Purines
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’
Question 39
What is the energy currency of the living cell?
A. GTP
B. NADH
C. FADH
D. ATP
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
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
Question 42
Who discovered nucleic acid?
A. Watson and Crick
B. Griffith
C. Friedrich Miescher
D. Walter Gilbert