CBSE 12 Biology Exam 2025 : Top 50 MCQs Questions & Answers for High Marks!

CBSE 12th exams are underway and your CBSE 12th Biology exam is scheduled for 25th march, 2025. You have just a few hours left for CBSE 12th Biology exam.

We have prepared Top 50 MCQs with answers covering all the important topics of CBSE Class 12 Biology syllabus.

Make sure to solve these MCQs and refer to the solutions to ensure that you are well prepared to score high in CBSE Class 12 Biology exam 2025.

CBSE 12th Biology 2025: Top 50 MCQs with Answers

1. What is the male reproductive organ of a flower?

a) Stigma

b) Anther

c) Ovary

d) Style

2. The process of pollen grains transfer from the anther to the stigma of a flower is called:

a) Fertilization

b) Pollination

c) Germination

d) Ovulation

3. Which of the following is not a method of self-pollination in flowers?

a) Cleistogamy

b) Wind pollination

c) Geitonogamy

d) Autogamy

4. In which part of the flower's pistil does fertilization occur?

a) Ovary

b) Style

c) Stigma

d) Ovule

5. In angiosperms, meiosis occurs during the formation of:

a) Pollen grains

b) Ovules

c) Endosperm

d) Embryo sac

6. What is the purpose of the pollen tube in plants?

a) To provide support to the pollen grain

b) To protect the pollen grain during transportation

c) To help in fertilization by carrying male gametes to the ovary

d) To store food for the developing embryo

7. The phenomenon where a single pollen grain germinates and produces two male gametes is called:

a) Binary fission

b) Double fertilization

c) Bipolar division

d) Triple fusion

8. The inner lining of the uterus, where the fertilised egg implants and develops, is called the:

a) Endometrium

b) Myometrium

c) Perimetrium

d) Cervix

9. The hormone responsible for milk production in mammary glands is:

a) Estrogen

b) Progesterone

c) Prolactin

d) Oxytocin

10. The process of shedding of the uterine lining along with blood is known as:

a) Ovulation

b) Fertilisation

c) Menstruation

d) Implantation

11. The maximum number of spermatozoa are stored in the:

a) Epididymis

b) Seminal vesicles

c) Vas deferens

d) Prostate gland

12. In humans, fertilisation typically occurs in the:

a) Uterus

b) Cervix

c) Vagina

d) Fallopian tube

13. Which of the following is not a barrier method of contraception?

a) Diaphragm

b) Condom

c) Copper-T

d) Cervical cap

14. Which method of contraception is known as the “morning-after pill”?

a) Oral contraceptive pill

b) Copper-T

c) Emergency contraception

d) Sterilization

15. Which contraceptive method provides protection against both unwanted pregnancies and sexually transmitted infections?

a) Oral contraceptive pill

b) Barrier methods (e.g., condom)

c) Intrauterine device (IUD)

d) Sterilization

👉 CBSE Class 12 Study Materials

CBSE Class 12 Syllabus 2024-25	CBSE Class 12 Previous Year Papers
NCERT Books For Class 12 Books	NCERT Class 12 Solutions
CBSE Class 12 Full Study Material	CBSE Class 12 Sample Paper 2024-25

16. In Mendel's experiments on pea plants, the trait that disappeared in the F1 generation but reappeared in the F2 generation is called:

a) Dominant trait

b) Recessive trait

c) Co-dominant trait

d) Linked trait

17. The term "homozygous" refers to an individual that has:

a) Two different alleles for a particular gene

b) Two identical alleles for a particular gene

c) Multiple alleles for a particular gene

d) No alleles for a particular gene

18. The genetic makeup of an individual is referred to as its:

a) Phenotype

b) Genotype

c) Allele

d) Homozygosity

19. A short piece of DNA, having 20 base pairs, was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown in the table.

	Number of nucleotide bases
	Adenine	Cytosine	Guanine	Thymine
Strand 1	4	4
Strand 2		5

How many nucleotides containing Adenine were present in strand 2?

a) 2

b) 4

c) 5

d) 7

20. What is the smallest part of a DNA molecule that can be changed by a point mutation?

a) Oligonucleotide
b) Codon

c) Gene

d) Nucleotide

21. The genetic code is said to be degenerate because:

a) Each amino acid has multiple codons

b) Each codon codes for multiple amino acids

c) The start codon codes for multiple amino acids

d) The stop codon codes for multiple amino acids

22. Which of the following is an example of a silent mutation?

a) Missense mutation

b) Nonsense mutation

c) Frame-shift mutation

d) None of the above

23. The enzyme responsible for adding telomeres at the ends of eukaryotic chromosomes is:

a) DNA polymerase

b) Primase

c) Telomerase

d) Ligase

24. The extinction of dinosaurs is associated with:

a) Volcanic eruptions

b) Asteroid impact

c) Climate change

d) Plate tectonics

25. The phenomenon where unrelated species evolve similar traits due to similar environmental pressures is called:

a) Convergent evolution

b) Divergent evolution

c) Coevolution

d) Adaptive radiation

26. The idea that evolution occurs in small, incremental steps over long periods of time is known as:

a) Gradualism

b) Punctuated equilibrium

c) Speciation

d) Adaptive radiation

27. The evolution of wings in birds and bats is an example of:

a) Convergent evolution

b) Divergent evolution

c) Coevolution

d) Parallel evolution

28. The evolutionary theory proposed by Charles Darwin is based on the concept of:

a) Inheritance of acquired traits

b) Natural selection

c) Genetic drift

d) Mutation

29. The causative agent of dengue fever is transmitted by:

a) Mosquitoes

b) Ticks

c) Fleas

d) Lice

30. The Widal test is used for the diagnosis of which of the following diseases?

a) Malaria

b) Tuberculosis

c) Dengue fever

d) Typhoid fever

31. Microbes used in the production of antibiotics belong to which group?
a) Fungi
b) Bacteria
c) Viruses
d) Protozoans

32. Which microorganism is commonly used in the production of alcohol through fermentation?

a) Saccharomyces cerevisiae
b) Aspergillus niger
c) Penicillium notatum
d) Escherichia coli

33. Which enzyme is produced by microorganisms to convert lactose into lactic acid during the production of curd?
a) Protease
b) Amylase
c) Lactase
d) Lactic acidase

34. Microbes are used in the production of biogas through the process of:
a) Fermentation
b) Photosynthesis
c) Respiration
d) Transpiration

35. The enzyme used to produce complementary DNA (cDNA) from an mRNA template is:
a) DNA polymerase
b) Reverse transcriptase
c) DNA ligase
d) Restriction enzyme

36. The technique used to amplify a specific region of DNA to produce multiple copies is called:
a) Recombinant DNA technology
b) DNA sequencing
c) PCR (Polymerase Chain Reaction)
d) Gel electrophoresis

37. Which restriction site is not present in pBR322 plasmid?
a) EcoRI
b) Hind III
c) Hind II
d) Sal I

38. pBR322 plasmid is resistant to which of the following antibiotics?
a) Ampicillin
b) tetracycline
c) Penicillin
d) both a and b

39. The correct full form of BT in Bt Cotton is;

a) Bacillus thuringensis

b) Bacillus thurinogiensis

c) Bacillus thuringiensis

d) Bacillus thoringiensis

40. Biodiversity refers to:
a) The variety of genetic traits in a population
b) The variety of species and ecosystems in a region
c) The total number of individuals in an ecosystem
d) The variety of physical environments in an area

41. The loss of biodiversity due to human activities is called
a) Evolution
b) Conservation
c) Extinction
d) Biodiversity

42. Which of the following is a direct threat to biodiversity?
a) Sustainable development
b) Habitat preservation
c) Pollution
d) Ecotourism

43. Which of the following is an in-situ conservation method?
a) Seed banks
b) Botanical gardens
c) National parks
d) Wildlife sanctuaries

44. Which of the following is an example of an endemic species?
a) Tiger (Panthera tigris)
b) Polar bear (Ursus maritimus)
c) Komodo dragon (Varanus komodoensis)
d) Giant panda (Ailuropoda melanoleuca)

45. The transfer of energy and nutrients between trophic levels in an ecosystem is known as
a) Decomposition
b) Food chain
c) Biomagnification
d) Photosynthesis

46. Which of the following statements is true about a food web in an ecosystem?
a) It represents the flow of energy in a single direction from producers to decomposers.
b) It consists of only a single chain of feeding relationships.
c) It shows the interconnectedness of multiple food chains.
d) It includes only primary consumers and decomposers.

47. Which of the following is an abiotic factor in an ecosystem?
a) Producers
b) Consumers
c) Temperature
d) Decomposers

48. Plant species having a wide range of genetical distribution evolve into a local population known as
a) Ecotype
b) Biome
c) Ecosystem
d) Population

49. Geometric representation of age structure is a characteristics of
a) Population
b) Land scape
c) Ecosystem
d) Biotic community

50. This capacity to generate a whole plant from any cell/explant is called
a) Pluripotency
b) Totipotency
d) Both a and b
c) None of these

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CBSE 12th Biology 2025: Top 50 MCQs with Answers