Explore topic-wise MCQs in Nucleic Acid Structure.

This section includes 79 Mcqs, each offering curated multiple-choice questions to sharpen your Nucleic Acid Structure knowledge and support exam preparation. Choose a topic below to get started.

1.

Histones
A. are negatively-charged globular proteins.
B. contain both -helix and -pleated sheet.
C. have molecular weights in excess of 100,000
D. contain high amounts of basic amino acids.
Answer» E.
Discussion
2.

Which is a characteristic of eukaryotic genetic material?
A. Eukaryotic genetic material consists of supercoiled circular DNA molecules complexed with proteins into chromosomes.
B. Eukaryotic genetic material consists of relaxed linear DNA molecules complexed with RNA into a 30 nm fiber.
C. Eukaryotic genetic material is compacted by wrapping the double-helix around histone proteins to form nucleosomes
D. Eukaryotic genetic material is compacted by folding linker regions around non-histone proteins to form a scaffold.
Answer» D. Eukaryotic genetic material is compacted by folding linker regions around non-histone proteins to form a scaffold.
Discussion
3.

Which is a property of both viral genetic material and bacterial genetic material?
A. Both can be double-stranded, circular DNA.
B. Both can be single-stranded, linear RNA.
C. Both can be compacted into inverted repeats.
D. Both can be compacted into plasmids.
Answer» B. Both can be single-stranded, linear RNA.
Discussion
4.

If the following experimental results were obtained, which would be evidence against DNA being the genetic material?
A. The base composition of DNA is the same in two different cells of the same organism.
B. The viral components labeled with 32P remain outside the cell during a successful infection.
C. The transforming factor isolated from a virulent bacterium is sensitive to deoxyribonucleases.
D. The base composition of DNA in an organism remains constant as the organism ages.
Answer» C. The transforming factor isolated from a virulent bacterium is sensitive to deoxyribonucleases.
Discussion
5.

Which property is shared by the five histone proteins?
A. They are acidic proteins with relatively large molecular weights.
B. They are multimeric proteins with high levels of Arg and Lys
C. They are fibrous proteins with high amounts of -helix.
D. They are globular proteins with a positive charge.
Answer» E.
Discussion
6.

Which of the following protein is the component of nucleoprotein?
A. Proline
B. Arginine
C. Histones
D. All of the above
Answer» D. All of the above
Discussion
7.

Which of the following statements is not true about RNA?
A. Does not have a double stranded structure
B. Thymine is present
C. Does not obey Chargaff s rule
D. The sugar contained in RNA is a ribose
Answer» C. Does not obey Chargaff s rule
Discussion
8.

Which of the following is true about Z-DNA helix?
A. It has alternating GC sequences
B. It is a permanent conformation of DNA
C. It tends to be found at the 3 end of the genes
D. It has fewer base pairs per turn than B-DNA
Answer» B. It is a permanent conformation of DNA
Discussion
9.

What is the full form of AMP?
A. Adenine mini-phosphate
B. Aldehyde mono-phosphate
C. Alcohol mono-phosphate
D. None of the above
Answer» E.
Discussion
10.

Which one of the following nucleic acids has a left handed helix?
A. M-RNA
B. T-RNA
C. A-DNA
D. Z-DNA
Answer» E.
Discussion
11.

Which of the following leads to disruption of nucleosomal structure?
A. Acetylation
B. Carboxylation
C. Phosphorylation
D. Methylation
Answer» E.
Discussion
12.

Arrangement of nucleotides in DNA can be seen by ____________
A. Ultracentrifuge
B. X-Ray crystallography
C. Light microscope
D. Electron microscope
Answer» C. Light microscope
Discussion
13.

According to Chargaff s rule, in a DNA molecule ____________
A. The amount of adenine and thymine is equal to the amount of guanine and cytosine
B. The amount of adenine and guanine is equal to the amount of thymine and cytosine
C. The amount of adenine and uracil is equal to the amount of guanine and cytosine
D. The amount of adenine and guanine is equal to the amount of uracil and cytosine
Answer» B. The amount of adenine and guanine is equal to the amount of thymine and cytosine
Discussion
14.

In most of the nucleotides, the phosphate group is attached to which carbon of pentose sugar?
A. C-1
B. C-2
C. C-4
D. C-5
Answer» E.
Discussion
15.

Which of the following statement is NOT true?
A. Works as chemical messenger
B. Co-enzymes
C. Co-factors
D. Energy carries
Answer» C. Co-factors
Discussion
16.

Match the following- 9. Where is DNA present?
A. Mitochondria
B. Nucleus
C. Cytoplasm
D. Both A and B
Answer» B. Nucleus
Discussion
17.

Which ratio is constant for DNA?
A. A + G / T + C
B. A + T / G + C
C. A + C / U + G
D. A + U / G + C
Answer» B. A + T / G + C
Discussion
18.

Where is RNA present?
A. Mitochondria
B. Nucleolus
C. Cytoplasm
D. Both B and C
Answer» E.
Discussion
19.

Which of the following is pyrimidine nucleotide?
A. Uracil
B. Cytosine
C. Thymine
D. All of the above
Answer» E.
Discussion
20.

Which of the following is not present in RNA?
A. uracil
B. adenine
C. thymine
D. guanine
Answer» D. guanine
Discussion
21.

If the compound does not contain the phosphate group, it is known as?
A. Nucleotide
B. Nucleoside
C. Both
D. None
Answer» C. Both
Discussion
22.

Which of the following is purine nucleotide?
A. Adenine
B. Uracil
C. Thymine
D. All of the above
Answer» B. Uracil
Discussion
23.

Number of hydrogen bonds between adenine and thymine?
A. 1
B. 2
C. 3
D. 4
Answer» C. 3
Discussion
24.

Number of hydrogen bonds between guanine and cytosine?
A. 1
B. 2
C. 3
D. 4
Answer» D. 4
Discussion
25.

nucleotides have how many components?
A. 2
B. 3
C. 4
D. 5
Answer» C. 4
Discussion
26.

Nucleotides are linked together to form nucleic acid through which type of bond?
A. Glycosidic bond
B. Phosphor-di-ester bond
C. Both
D. None
Answer» C. Both
Discussion
27.

Nucleic acids combine with which biomolecule?
A. Fats
B. Carbohydrates
C. Lipids
D. Proteins
Answer» E.
Discussion
28.

Which of the following double-stranded DNA molecules would denature at about the same temperature as the double-stranded molecule containing a 5 -(GA)20-3 strand?
A. a molecule which contains a (GC)20 strand
B. a molecule which contains a (TA)20 strand
C. a molecule which contains a (GACT)10 strand
D. a molecule which contains a (GGGA)10 strand
Answer» D. a molecule which contains a (GGGA)10 strand
Discussion
29.

Which of the following forces can stabilize a normal DNA double-helix?
A. Base-stacking is a non-covalent interaction that occurs between the relatively hydrophobic bases in the interior of the helix.
B. Base-pairing is a non-covalent interaction that occurs between adjacent bases in the same strand of the DNA molecule.
C. The hydrophilic sugar-phosphate groups are on the exterior of the helix where they can interact with each other.
D. The deoxyribose rings form N-glycosidic bonds with the phosphate groups that link neighboring nucleotides.
Answer» B. Base-pairing is a non-covalent interaction that occurs between adjacent bases in the same strand of the DNA molecule.
Discussion
30.

When this single strand binds to a complementary DNA strand to form a B-DNA structure,
A. half the base-pairs will be A-G pairs and half will be C-T pairs.
B. each base will form at least two hydrogen bonds with a base in the opposite strand.
C. the two strands will form an antiparallel left-handed helix with 12 basepairs per turn.
D. there will be covalent phosphodiester bonds between the two strands.
Answer» C. the two strands will form an antiparallel left-handed helix with 12 basepairs per turn.
Discussion
31.

When this single strand binds to a complementary DNA strand,
A. the complementary strand has the sequence 5 -(CT)20-3 and a cruciform structure could form.
B. the complementary strand has the sequence 5 -(CT)20-3 and a Z-DNA structure could form.
C. the complementary strand has the sequence 5 -(TC)20-3 and an H-DNA structure could form.
D. the complementary strand has the sequence 5 -(TC)20-3 and a hairpin structure could form.
Answer» D. the complementary strand has the sequence 5 -(TC)20-3 and a hairpin structure could form.
Discussion
32.

Which of the following nucleotides is not present in DNA?
A. AMP
B. GMP
C. CMP
D. UMP
Answer» E.
Discussion
33.

Which of the following nucleotides is not present in RNA?
A. AMP
B. GMP
C. CMP
D. TMP
Answer» E.
Discussion
34.

Which of the following is false about denaturation?
A. Disruption of hydrogen bonds
B. Disruption of phosphodiester linkage
C. Loss of helical structure of DNA
D. It is resulted as a result of change in pH or increase in temperature
Answer» C. Loss of helical structure of DNA
Discussion
35.

DNA denaturation is measured by absorbance at ___________
A. 220nm
B. 230nm
C. 250nm
D. 260nm
Answer» E.
Discussion
36.

What happens in hyperchromicity?
A. When DNA is in bound form, there is decrease in absorption of UV light
B. When DNA is in bound form, there is increase in absorption of UV light
C. When DNA is in unbound form, it is more stable
D. When DNA is in unbound form, there is increase in absorption of UV light
Answer» E.
Discussion
37.

What happens in hypochromicity?
A. When DNA is in bound form, there is decrease in absorption of UV light
B. When DNA is in bound form, there is increase in absorption of UV light
C. When DNA is in unbound form, it is more stable
D. When DNA is in unbound form, there is decrease in absorption of UV light
Answer» B. When DNA is in bound form, there is increase in absorption of UV light
Discussion
38.

Which of the following involves carrying genetic information from DNA for protein synthesis?
A.
B. B.
C. C.
D. D.
Answer» B. B.
Discussion
39.

Identify the purine base of nucleic acids in the following.
A. Cytosine
B. Thymine
C. Uracil
D. Adenine
Answer» E.
Discussion
40.

Which structural feature is shared by both uracil and thymine?
A. Both contain two keto groups.
B. Both contain one methyl group.
C. Both contain a five-membered ring.
D. Both contain three nitrogen atoms.
Answer» B. Both contain one methyl group.
Discussion
41.

Purine base found in RNA is
A. Cytosine
B. Thymine
C. Guanine
D. Uracil
Answer» D. Uracil
Discussion
42.

Which of the following nucleotide contains only ribose sugar and not deoxyribose?
A. Thymine pentose sugar-phosphate
B. Uracil pentose sugar-phosphate
C. Thymine pentose sugar-phosphate
D. Cytosine pentose sugar-phosphate
Answer» C. Thymine pentose sugar-phosphate
Discussion
43.

The sugar molecule present in nucleotide is
A. triose
B. tetrose
C. pentose
D. hexose
Answer» D. hexose
Discussion
44.

Find the correct statement about phosphodiester linkage between adjacent nucleotides in nucleic acids
A. 3 -phosphate of one nucleotide joins the 3 -hydroxyl of the next nucleotide
B. 3 -phosphate of one nucleotide joins the 5 -hydroxyl of the next nucleotide
C. 5 -phosphate of one nucleotide joins the 5 -hydroxyl of the next nucleotide
D. 5 -phosphate of one nucleotide joins the 3 -hydroxyl of the next nucleotide
Answer» E.
Discussion
45.

Nucleoside contains
A. base-sugar
B. base-phosphate
C. base-sugar-phosphate
D. sugar-phosphate
Answer» B. base-phosphate
Discussion
46.

ATP is a
A. nucleoside
B. nucleotide
C. vitamin
D. nucleic acid
Answer» C. vitamin
Discussion
47.

A phosphodiester bond is present in
A. Nucleic acids in a nucleotide
B. Monosaccharides in a polysaccharide
C. Amino acids in a polypeptide
D. Fatty acids in a diglyceride
Answer» B. Monosaccharides in a polysaccharide
Discussion
48.

Building blocks of nucleic acids are ____________
A. Nucleotides
B. Nucleosides
C. Amino acids
D. Histones
Answer» B. Nucleosides
Discussion
49.

Which of the following is false about purine and pyrimidine bases?
A. They are hydrophobic and relatively insoluble in water at the near-neutral pH of the cell
B. At acidic or alkaline pH the bases become charged and their solubility in water increases
C. Purines have two rings in their structure, but pyrimidine bases have only one ring
D. At acidic or alkaline pH the bases become charged and their solubility in water decreases
Answer» E.
Discussion
50.

Group of adjacent nucleotides are joined by ____________
A. Phosphodiester bond
B. Peptide bond
C. Ionic bond
D. Covalent bond
Answer» B. Peptide bond
Discussion