Imp mcqs on Molecular Basis of Inheritance..(NEET/AIIMS) PDF Download

1. A. At the time of Mendel, the nature of the factors regulating the pattern of inheritance
was very clear.
B. The determination of complete nucleotide sequence of human during last 2 decades
has set in a new era of genomics.
C. In double stranded DNA A G/T C≠ 1
D. DNA is acid but DNase is not an enzyme
(a) All are correct
(b) All are incorrect
(c) Only B is correct
(d) Only D is correct

2. DNA –
A. Acts as genetic material in all cellular organisms
B. Was discovered by F. Meischer who named it as Nuclein
C. Is acidic in nature
D. Cannot be digested by DNase
Correct information is ?
(a) A, C
(b) A, B, C, D
(c) B, C, D
(d) A, B, C

3. In 1953 J. Watson and F. Crick proposed Double helix model of DNA and got Nobel Prize.
Their model of DNA was based on –
A. X-ray diffraction of DNA produced by M. Wilkins and R. Franklin
B. Griffith`s experiment
C. Hershey – Chase experiment
D. Chargaff`s rule of base equivalence (A G / T C = 1 )
(a) A, D
(b) A, B, C, D
(c) B, C, D
(d) A, B, C

4.The phosphodiester bonds between nucleotides are called –
(a) Backbone of DNA
(b) Steps of DNA
(c) Imidazole
(d) Hydrophobic attraction

5. In one polynucleotide chain of a DNA molecule the ratio of A T / G C is 0.3. what is the
A G / T C ratio of the entire DNA molecule
(a) 0.3
(b) 0.6
(c) 1.2
(d) 1

6. Which one / ones did not affect the transformation?
A. DNAase
B. RNAase
C. Peptidase
D. Lipase
(a) A, C
(b) A, B, C, D
(c) B, C, D
(d) A, B, C

7. In DNA you find which types(s) of bond
A. Phosphodiester
B. Phosphoester
C. Hydrogen
D. Glycosidic bond
(a) C, D
(b) A, B, C, D
(c) B, C, D
(d) A, B, C

8. A nucleosome consists of –
A. RNA
B. Protein
C. Histone octamer
D. 200 bps long DNA
(a) C, D
(b) A, B, C, D
(c) B, C, D
(d) A, B, C

9. A. Both DNA and RNA are able to mutate
B. RNA being unstable, mutates at a faster rate
C. RNA is also known to be catalytic, hence reactive
D. The presence of thymine at place of uracil confers additional stability to DNA
(a) All are correct
(b) All are incorrect
(c) Only A, B and D are correct
(d) Only D is correct

10. Protein synthesis involves
A. Transcription
B. Translation
C. Transversion
D. Translocation
(a) A, B
(b) A, B, C, D
(c) B, C, D
(d) A, B C

11. Antiparallel relationship of the two strands of DNA refers to the –
(a) Strands being the opposite of parallel –they are twisted
(b) Strands providing alternate branching
(c) One strand runs 5` → 3` and other in 3` → 5` direction
(d) Both strands run in 5` → 3` direction

12. Nucleic acids are made up of
A. Nitrogenous bases
B. Amino acids
C. Sugar
D. Phosphate
(a) A, C, D
(b) A, D
(c) B, C, D
(d) A, B, C

13. Characteristic(s) of most DNA is / are
A. A pairs with T by 2 hydrogen bonds
B. Antipolarity of complementary chains
C. 20 A° diameter
D. 10 bps / turn
(a) A, C
(b) A, B, C, D
(c) B, C, D
(d) A, B, C

14. DNA has a alternate grooves –
(a) One major and one minor
(b) Two major and one minor
(c) One major and two minor
(d) Two major and two minor

15. Similarity between DNA and RNA is that both have
A. Adenine
B. Guanine
C. Thymine
D. Cytosine
(a) A, C
(b) A, B, C, D
(c) B, C, D
(d) A, B, D

16. The experimental proof for DNA as genetic material comes from
A. Transformation
B. Transduction (Viral infection)
C. Conjugation
D. Mutation
(a) A, C
(b) A, B, C, D
(c) C, D
(d) A, B

17. Frederick Griffith conducted experiments testing the virulence of two strains of
Streptococcus (R-strain and S-strain).
His experiment has 4 specific treatments to it.
Treatment 1, he injected mice with the R-strain and the mice lived.
Treatment 2, he injected mice with the S-strain and the mice died.
Treatment 3, he injected mice with heat-killed S-strain and the mice lived.
Treatment 4, he injected mice with heat-killed S-strain and the mice died.
Which treatment in his experiment is considered a control treatment?
(a) Treatment 3 is the control treatment
(b) Treatment 1 is the control treatment
(c) There are no control treatments in this experiment
(d) Treatments 1 and 2 are control treatments.

18. Why are mice killed by smooth (S) strains of Streptococcus, but not rough (R) Strains?
(a) Rough strains are virulent, and smooth strains are not.
(b) Rough strains have a polysaccharide capsule that makes the mouse immune system
recognize and destroy them.
(c) Smooth strains have a polysaccharide capsule, which hides them from the mouse
immune system.
(d) Smooth strains grow faster than rough strains.
19. If the DNA of this virus was labeled with 32 P and the protein of the virus was labeled
with 35S, which molecule(s) would be present inside the cells?
(a) 35 S and 32 P
(b) 35 S only
(c) 32 P only
(d) Neither molecule would be present inside the cell.

20. Which of the following statements is correct?
I. The biochemical nature of genetic material was not defined from the
experiments conducted by Griffith.
II. Working on transformation Avery et al concluded DNA is genetic material but
not all biologists were convinced.
III. RNA is the genetic material in TMV, QB becteriophage etc.
IV. DNA is the predominant genetic material while RNA performs dynamic functions
of messenger and adapter.
V. Viruses having DNA genome and having shorter life span mutate and evolve
faster...
(a) All
(b) I and II
(c) All except V
(d) III and IV

ANSWERS
1. Ans.(c) Only B is correct
2. Ans.(d) A, B, C
3. Ans.(a) A, D
4. Ans.(a) Backbone of DNA
5. Ans.(d) 1
6. Ans.(c) B, C, D
7. Ans.(b) A, B, C, D
8. Ans.(a) C, D
9. Ans.(a) All are correct
10. Ans.(a) A, B
11. Ans.(c) One strand runs 5` → 3` and other in 3` → 5` direction
12. Ans.(a) A, C, D
13. Ans.(b) A, B, C, D
14. Ans.(c) One major and two minor
15. Ans.(d) A, B, D
16. Ans.(d) A, B
17. Ans.(d) Treatments 1 and 2 are control treatments.
18. Ans.(c) Smooth strains have a polysaccharide capsule, which hides them from
the mouse immune system.
19. Ans.(c) 32 P only
20. Ans.(c) All except V