CBSE Class 12 Biology Sample Paper 2023 Solved

SECTION - A

Question

1. An infertile couple was advised to undergo In vitro fertilization by the doctor. Out of the options given below, select the correct stage for transfer to the fallopian tube for successful results?
(a) Zygote only
(b) Zygote or early embryo upto 8 blastomeres
(c) Embryos with more than 8 blastomeres
(d) Blastocyst Stage

Answer : B

2. Given below are four contraceptive methods and their modes of action. Select the correct match:  

(a) a)–(i) b)–(ii) c)– (iii) d)–(iv)
(b) a)–(ii) b)–(iii) c)–(iii) d) – (i)
(c) a)–(iii) b)–(iv) c)–(ii) d)–(i)
(d) a)–(iv) b)–(i) c)– (iii) d)–(ii)

Answer : C

3 Which of the following amino acid residues will constitute the histone core?
(a) Lysine and Arginine
(b) Asparagine and Arginine
(c) Glutamine and Lysine
(d) Asparagine and Glutamine

Answer : A

4 Evolutionary convergence is development of a
(a) common set of functions in groups of different ancestry.
(b) dissimilar set of functions in closely related groups.
(c) common set of structures in closely related groups.
(d) dissimilar set of functions in unrelated groups.

Answer : A

5. Apis mellifera are killer bees possessing toxic bee venom. Identify the treatment and the type of immunity developed from the given table to treat a person against the venom of this bee. Remedy Immunity
(a) Inactivated proteins Active
(b) Proteins of the venom Passive
(c) Preformed antibodies Passive
(d) Dead micro-organisms Active

Answer : C

6. Interferons are most effective in making non-infected cells resistant against the spread of which of the following diseases in humans?
(a) ascariasis
(b) ringworm
(c) amoebiasis
(d) AIDS

Answer : D

7. Which of the following water samples in the table given below, will have a higher concentration of organic matter?  

Answer : A

8. The figure below shows the structure of a plasmid.  

A foreign DNA was ligated at BamH1. The transformants were then grown in a medium containing antibiotics tetracycline and ampicillin.
Choose the correct observation for the growth of bacterial colonies from the given table  

Answer : B

9. Swathi was growing a bacterial colony in a culture flask under ideal laboratory conditions where the resources are replenished. Which of the following equations will represent the growth in this case?
(Where population size is N, birth rate is b, death rate is d, unit time period is t, and carrying capacity is K).
(a) dN/dt = KN
(b) dN/dt = r N
(c) dN/dt = r N(K-N/K)
(d) dN/dt = r N(K+N/K)

Answer : B

10. Sea Anemone gets attached to the surface of the hermit crab. The kind of population interaction exhibited in this case is
(a) amensalism.
(b) commensalism.
(c) mutualism.
(d) parasitism.

Answer : B

11. Which of the following food chains is the major conduit for energy flow in terrestrial and aquatic ecosystems respectively? Terrestrial Ecosystem Aquatic Ecosystem
(a) Grazing Grazing
(b) Detritus Detritus
(c) Detritus Grazing
(d) Grazing Detritus

Answer : C

12 Which of the following is an example of ex situ conservation?
(a) Sacred Groves
(b) National Park
(c) Biosphere Reserve
(d) Seed Bank

Answer : D