Class 12 CBSE Biology Question Paper 2023

Maximum Marks: 70

Time Allowed: Three hours

All questions are compulsory.

The question paper has five sections and 33 questions. All questions are compulsory.

Section–A has 16 questions of 1 mark each; Section–B has 5 questions of 2 marks each; Section– C has 7 questions of 3 marks each; Section– D has 2 case-based questions of 4 marks each; and Section–E has 3 questions of 5 marks each.

There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.

Wherever necessary, neat and properly labeled diagrams should be drawn

Class 12 CBSE Biology Question Paper 2023

Section-A

Question 1

Solution

Question 2

Important attributes belonging to a population but not to an individual are: (i) Birth rate and death rate (ii) Male and female (iii) Birth and death (iv) Sex-ratio Select the correct option from the given options : (a) (i) only(b) (ii) only (c) (ii) and (iii) (d) (i) and (iv)

Solution

Question 3

Many copepods live on the body surface of marine fish. This relationship is an example of: (a) Commensalism (b) Parasitism (c) Amensalism (d) Mutalism

Solution

Question 4

Given below is the restriction site of a restriction endonuclease Pst-I and the cleavage sites on a DNA molecule.

Solution

Question 5

Solution

Question 6

Solution

Question 7

Given below are the list of the commercially important products and their source organisms. Select the option that gives the correct matches.

Solution

Question 8

Tetanus antitoxin (Tetanus toxoid) when injected into the human body it immediately provides : (a) Innate immunity (c) Auto immunity (b) Passive immunity (d) Active immunity

Solution

Question 9

The primary productivity in an ecosystem is expressed as : (a) gm-2 yr-1 (b) gm-2 yr (c) K cal m2 yr-1 (d) K cal m-²

Solution

Question 10

Solution

Question 11

The sixth extinction in progress currently is different from all previous extinctions on earth as it is : (a) 10-100 times faster (c) 100-10000 times faster (b) 100-1000 times faster (d) 1000-10000 times faster

Solution

Question 12

At which stage during evolution did human use hides to protect their bodies and buried their dend? (n) Homo habilis (b) Neanderthal man (c) Java man (d) Homo erectus

Solution

Question 13

Assertion (A): Decomposition process is slower if detritus is rich in lignin and cutin. Reason (R): Decomposition is largely an oxygen requiring process.

Solution

Question 14

Assertion (A): Determining the sex of an unborn child followed by MTP is an illegal practice. Reason (R): Amniocentesis is a practice to test the presence of genetic disorders also.

Solution

Question 15

Assertion (A): In Thalassemia an abnormal myoglobin chain is synthesized due to a gene defect. Reason (R): α-Thalassemia is controlled by genes HBA1 and HBA2 on chromosome 16

Solution

Question 16

Assertion (A): Synthetic oligonucleotide polymers are used during Annealing in a PCR. Reason (R): The primers bind to the double stranded DNA at their complementary regions.

Solution

SECTION-B

Question 17

(a) Name (i) a GM cereal crop having enhanced nutritional value, (ii) the nutrient it is rich in. (b) State any two benefits of Genetically modified crops.

Solution

Question 18

By using Punnett square depict the genotypes and phenotypes of test crosses (where green pod colour (G) is dominant over yellow pod colour (g)) in Garden pea with unknown genotype.

Solution

Question 19

Solution

Question 20

The graph given below shows the number of primordial follicles per ovary in women at different ages. Study the graph and answer the questions that follow.

Solution

Question 21

"Some species of insects and frogs have evolved with various specific features that help them from being detected." (a) Justify the statement giving reasons. (b) Mention any two such features.

Solution

SECTION-C

Question 22

(a) "Plasmodium protozoan needs both a mosquito and a human host for its continuity." Explain. OR (b) We all must work towards maintaining good health because 'health is wealth'. Enlist any six ways of achieving good health.

Solution

Question 23

"Biodiversity plays a major role in many ecosystem services that nature provides." (a) Describe any two broadly utilatarian arguments to justify the given statement. (b) State one ethical reason of conserving biodiversity.

Solution

Question 24

Name and explain a surgical contraceptive method that can be adopted by the male partner of a couple.

Solution

Question 25

Human Genome Project (HGP) was a mega project launched in the year 1990 with some important goals. (a) Enlist any four prime goals of HGP. (b) Name any one common non-human animal model organism which has also been sequenced thereafter.

Solution

Question 26

One of the major approaches of crop improvement programme is Artificial Hybridisation. Explain the steps involved in making sure that only the desired pollen grain pollinate the stigma of a bisexual flower by a plant breeder.

Solution

Question 27

Mention Darwin's observations made on finches during his visit to Galapagos Islands. Write the explanation given by Darwin on his observations.

Solution

Important attributes belonging to a population but not to an individual are:
(i) Birth rate and death rate
(ii) Male and female
(iii) Birth and death
(iv) Sex-ratio
Select the correct option from the given options :
(a) (i) only
(b) (ii) only
(c) (ii) and (iii)
(d) (i) and (iv)

Many copepods live on the body surface of marine fish. This relationship is an example of:
(a) Commensalism
(b) Parasitism
(c) Amensalism
(d) Mutalism

Tetanus antitoxin (Tetanus toxoid) when injected into the human body it immediately provides :
(a) Innate immunity
(c) Auto immunity
(b) Passive immunity
(d) Active immunity

The primary productivity in an ecosystem is expressed as :
(a) gm-2 yr-1
(b) gm-2 yr
(c) K cal m2 yr-1
(d) K cal m-²

The sixth extinction in progress currently is different from all previous extinctions on earth as it is :
(a) 10-100 times faster
(c) 100-10000 times faster
(b) 100-1000 times faster
(d) 1000-10000 times faster

At which stage during evolution did human use hides to protect their bodies and buried their dend?
(n) Homo habilis
(b) Neanderthal man
(c) Java man
(d) Homo erectus

Assertion (A): Decomposition process is slower if detritus is rich in lignin and cutin.
Reason (R): Decomposition is largely an oxygen requiring process.

Assertion (A): Determining the sex of an unborn child followed by MTP is an illegal practice.
Reason (R): Amniocentesis is a practice to test the presence of genetic disorders also.

Assertion (A): In Thalassemia an abnormal myoglobin chain is synthesized due to a gene defect.
Reason (R): α-Thalassemia is controlled by genes HBA1 and HBA2 on chromosome 16

Assertion (A): Synthetic oligonucleotide polymers are used during Annealing in a PCR.
Reason (R): The primers bind to the double stranded DNA at their complementary regions.

(a) Name (i) a GM cereal crop having enhanced nutritional value, (ii) the nutrient it is rich in.
(b) State any two benefits of Genetically modified crops.

"Some species of insects and frogs have evolved with various specific features that help them from being detected."
(a) Justify the statement giving reasons.
(b) Mention any two such features.

(a) "Plasmodium protozoan needs both a mosquito and a human host for its continuity." Explain.
OR
(b) We all must work towards maintaining good health because 'health is wealth'. Enlist any six ways of achieving good health.

"Biodiversity plays a major role in many ecosystem services that nature provides."
(a) Describe any two broadly utilatarian arguments to justify the given statement.
(b) State one ethical reason of conserving biodiversity.

Human Genome Project (HGP) was a mega project launched in the year 1990 with some important goals.
(a) Enlist any four prime goals of HGP.
(b) Name any one common non-human animal model organism which has also been sequenced thereafter.