Biology Multiple Choice Questions and Answers for Different Competitive Exams

Multiple Choice Questions on Nucleic acid

1. The pentoses in nucleotides are 
a) in β-furanose form
b) in α-furanose form
c) Both
d) none of the above

2. To identify self DNA from non-self DNA, the self DNA may be
a) glycosylated
b) carboxylated
c) phosphorylated
d) methylated

3. Functions of nucleotide includes
a) information storage and transmission
b) storage of chemical energy
c) cell signalling
d) All of the above

4. Choose the best option
a) proteins has catalytic activity
b) Proteins and RNA have catalytic activity
c) Proteins, RNA and antibodies have catalytic activity
d) Proteins, RNA, antibodies and phospholipids have catalytic activity

5. The backbone of DNA is
a) hydrophilic
b) hydrophobic
c) nuetral
d) Both hydrophilic and hydrophobic

6. Which is the most stable form of DNA under normal physiological conditions
a) A-DNA
b) B-DNA
c) Z-DNA
d) H-DNA

7. As far as the absorbance of DNA at 260nm. Which of the following is correct?
a) individual nucleotides>ss DNA>dsDNA
b) dsDNA>ssDNA> individual nucleotides
c) ssDNA>dsDNA> individual nucleotides
d) absorbance remains same

8. Which of the following statement is true?
a) DNA is more stable than RNA in alkaline condition because of the presence of 3’OH
b) DNA is more stable than RNA in alkaline condition because of the presence of 2’ H compared to RNAs 2’OH
c) RNA is more stable than DNA in alkaline condition because of the presence of 2’ and 3’OH compared to DNAs 2’H and 3’OH
d) Both are equally stable in alkaline condition

9. Dehydration of DNA samples may induce the formation of
a) A-DNA
b) B-DNA
c) Z-DNA
d) H-DNA

10. An increase in temperature of a DNA sample causes change in
a) absorbance at 260nm
b) viscosity
c) phosphodiester linkage
d) absorbance and viscosity

11. RNA-DNA hybrids are
a) more stable than  DNA-DNA hybrid
b) more stable than  RNA-RNA hybrid
c) less stable than RNA-RNA hybrid
d) less stable than RNA-RNA hybrid and DNA-DNA hybrid

12. An increase Tm (melting temperature) for a ds-DNA may be due to high content of
a) A+G
b) A+T
c) C+G
d)none of the above

13. Thymine is present in
a) prokaryotic mRNA
b) mammalian mRNA
c) ribosomal RNA
d) tRNA

14RNA is genetic material in
a)  some virusus and prokaryotes
b) some viruses only
c) some virusus, prokaryotes and some primitive eukaryotes
d) none of the above

15. DNA has
a) autocatalytic function
b) heterocatalytic function
c) both autocatalytic and heterocatalytic function
d) none of the above

Free online MCQ test on:  Nucleic acid -> DNA -> DNA Structure-> RNA
Answers: 
1- a) in β-furanose form (closed 5-membered ring
2- d) methylated.
3- d) All of the above
4-    c) Proteins, RNA and antibodies have catalytic activity.
RNA with catalytic activity: ribozymes
Antibodies with catalytic activity-abzymes
5- a) hydrophilic. The OH group  of sugar residue form H-bond with water
6- b) B-DNA
7- a) individual nucleotides>ss DNA>dsDNA
The reason for absorbance (A260 in DNA) is N2 bases. In ss DNA, N2 bases are  exposed so more A260 than ds DNA. In free nucleotides, N2 bases are much more exposed and free so high A260 than ss and ds DNA.
8- b) DNA is more stable than RNA in alkaline condition because of the presence of 2’ H compared to RNAs 2’OH
9- a) A-DNA
10- d) absorbance and viscosity
11- d) less stable than RNA-RNA hybrid and DNA-DNA hybrid
12- c) C+G has three H-bonds compared to two in A=T. So more temperature is needed for denaturation.
13- d) tRNA. t RNA has thymine and many unusual bases.
14- b) some viruses only
15- c) both autocatalytic and heterocatalytic function
Autocataytic function: DNA replication
Heterocatalytisc function:  directs synthesis of RNA and proteins

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