If you are about to take the CBSE Class 12 Biology Board Exam 2025 tomorrow (25th March 2025) and are facing trouble with final revision, then this article is for you. This article provides Top 50 MCQs for examinees to get assistance in their last-minute revision. These questions cover all the important topics included in the updated CBSE 12th Syllabus 2025. The correct answers are also provided so that the students can check their preparation status. Students will also be able to gain a better understanding of key concepts by solving these questions. Go through the top 50 MCQs which are important for appearing in the CBSE 12th Biology Board Exam 2025!
CBSE 12th Biology Paper Structure 2025
The table below shows the CBSE Class 12 Biology Question Paper 2025 format:
| Particulars | Details |
| Total Questions | 33 |
| Total Time | 3 Hours |
| Max Marks | 70 |
| Section A | 16 Question (1 Mark each), MCQs, and Assertion and Reason Based Questions |
| Section B | 5 Questions (2 Mark each) |
| Section C | 7 Questions (3 Mark each) |
| Section D | 2 Case Study-based questions (4 Mark each) |
| Section E | 3 Questions (5 Mark each) |
CBSE 12th Biology Top 50 MCQs for Board Exam 2025
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
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 trai
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
c) Both a and b
d) None of these
