CBSE Class 12 Biology Exam 2026: Top 50 MCQs with Answers for High Score in Exam!

CBSE Class 12th Biology Important MCQs: Ace the CBSE Class 12th Biology Board Exam 2026 with Top 50 MCQs. The CBSE Class 10th Biology Board Exam is fast approaching on March 27th, 2026. To help students secure high scores, particularly in the Multiple-Choice Questions (MCQs) section, we have curated a vital resource.

This compilation features the top 50 high-weightage MCQs, sourced from previous years' question papers and official CBSE sample papers. Solving these questions, which cover all essential chapter topics, is an excellent way to revise thoroughly and boost your exam confidence and performance. Detailed answers are included for efficient preparation.

CBSE Class 12th Biology Paper: Key Highlights

CBSE Class 12th Biology Exam Top 50 MCQs with Answers

Here are 50 important multiple-choice questions (MCQs) from all chapters in your 12th Biology syllabus along with their answers:

1. Which of the following is a non-albuminous seed?

   (A) Wheat (B) Maize (C) Pea (D) Castor

   Answer: (C) Pea

2. The part of the gynoecium that determines the compatible nature of pollen is:

   (A) Stigma (B) Style (C) Ovary (D) Thalamus

   Answer: (A) Stigma

3. Identify the mismatched pair:

   (A) Tuber - Potato (B) Rhizome - Ginger (C) Bulbil - Agave (D) Offset - Banana

   Answer: (D) Offset - Banana (Correct is Water Hyacinth)

4. The function of the filiform apparatus is to:

   (A) Recognize compatible pollen (B) Stimulate division of generative cell (C) Guide the entry of pollen tube (D) Produce nectar

   Answer: (C) Guide the entry of pollen tube

5. Triple fusion in angiosperms involves the fusion of:

   (A) Two male gametes and one egg (B) One male gamete and two polar nuclei (C) Two eggs and one male gamete (D) One male gamete and one synergid

   Answer: (B) One male gamete and two polar nuclei

6. Which hormone is responsible for the secretion of milk after parturition?

   (A) Estrogen (B) Progesterone (C) Prolactin (D) Relaxin

   Answer: (C) Prolactin

7. The middle piece of a human sperm contains:

   (A) Nucleus (B) Centriole (C) Mitochondria (D) Acrosome

   Answer: (C) Mitochondria

8. The primary female sex organ is:

   (A) Uterus (B) Ovary (C) Vagina (D) Fallopian tube

   Answer: (B) Ovary

9. Vasa efferentia are the ductules leading from:

   (A) Testicular lobules to rete testis (B) Rete testis to epididymis (C) Vas deferens to epididymis (D) Epididymis to urethra

   Answer: (B) Rete testis to epididymis

10. The first sign of a growing fetus may be noticed by:

    (A) Movement of the fetus (B) Formation of limbs (C) Listening to the heart sound (D) Appearance of hair

    Answer: (C) Listening to the heart sound

11. Which of the following is a "World Population Day"?

    (A) 5th June (B) 11th July (C) 1st December (D) 7th April

    Answer: (B) 11th July

12. The statutory marriageable age for females in India is:

    (A) 16 years (B) 18 years (C) 21 years (D) 25 years

    Answer: (B) 18 years

13. Copper-T prevents pregnancy by:

    (A) Preventing ovulation (B) Preventing fertilization (C) Inhibiting implantation (D) Both B and C

    Answer: (D) Both B and C

14. Mendel’s last law is the:

    (A) Law of Segregation (B) Law of Dominance (C) Law of Independent Assortment (D) Law of Unit Characters

    Answer: (C) Law of Independent Assortment

15. A cross between a tall plant (TT) and a short plant (tt) resulted in all tall plants in F1 because:

    (A) Tallness is recessive (B) Tallness is dominant (C) Shortness is dominant (D) It was co-dominance

    Answer: (B) Tallness is dominant

16. The phenotype ratio of a monohybrid F2 generation is:

    (A) 1:2:1 (B) 3:1 (C) 9:3:3:1 (D) 1:1

    Answer: (B) 3:1

17. Which nitrogenous base is absent in DNA?

    (A) Adenine (B) Guanine (C) Uracil (D) Thymine

    Answer: (C) Uracil

18. The "beads on a string" structure in chromatin are:

    (A) Genes (B) Nucleosomes (C) Centromeres (D) Chromatids

    Answer: (B) Nucleosomes

19. The process of copying genetic information from DNA to RNA is:

    (A) Replication (B) Translation (C) Transcription (D) Reverse Transcription

    Answer: (C) Transcription

20. Who proposed the "Operon Model"?

    (A) Watson and Crick (B) Jacob and Monod (C) Meselson and Stahl (D) Hershey and Chase

    Answer: (B) Jacob and Monod

21. The theory of "Natural Selection" was given by:

    (A) Lamarck (B) Darwin (C) Hugo de Vries (D) Louis Pasteur

    Answer: (B) Darwin

22. Wings of a butterfly and wings of a bird are examples of:

    (A) Homologous organs (B) Analogous organs (C) Vestigial organs (D) Atavism

    Answer: (B) Analogous organs

23. The "Big Bang Theory" explains the origin of:

    (A) Life (B) Universe (C) Earth (D) Solar System

    Answer: (B) Universe

24. Which of the following is a viral disease?

    (A) Typhoid (B) Malaria (C) Common Cold (D) Amoebiasis

    Answer: (C) Common Cold

25. The antibody responsible for allergic reactions is:

    (A) IgG (B) IgA (C) IgE (D) IgM

    Answer: (C) IgE

26. "Malaria" is transmitted by:

    (A) Male Anopheles (B) Female Anopheles (C) Culex (D) Aedes

    Answer: (B) Female Anopheles

27. The test used for diagnosing Typhoid is:

    (A) ELISA (B) Widal Test (C) PCR (D) MRI

    Answer: (B) Widal Test

28. Inbreeding depression is caused by:

    (A) Cross-breeding (B) Out-crossing (C) Continuous close inbreeding (D) Interspecific hybridization

    Answer: (C) Continuous close inbreeding

29. "Atlas 66" is a variety of:

    (A) Rice (B) Maize (C) Wheat (D) Mustard

    Answer: (C) Wheat

30. The most common bio-fertilizer used in paddy fields is:

    (A) Nostoc (B) Rhizobium (C) Azolla (D) Oscillatoria

    Answer: (C) Azolla

31. The "Baker’s Yeast" is:

    (A) Saccharomyces cerevisiae (B) Propionibacterium (C) Lactobacillus (D) Penicillium

    Answer: (A) Saccharomyces cerevisiae

32. Restriction enzymes are also known as:

    (A) Biological stitchers (B) Molecular scissors (C) Vectors (D) Plasmids

    Answer: (B) Molecular scissors

33. The first restriction endonuclease discovered was:

    (A) EcoRI (B) HindII (C) BamHI (D) PstI

    Answer: (B) HindII

34. PCR stands for:

    (A) Polymerase Chain Reaction (B) Protein Chain Reaction (C) Poly Chain Reaction (D) Primary Chain Reaction

    Answer: (A) Polymerase Chain Reaction

35. The first transgenic cow was:

    (A) Dolly (B) Rosie (C) Tracy (D) Polly

    Answer: (B) Rosie

36. Bt cotton is resistant to:

    (A) Insects (B) Fungi (C) Salt (D) Drought

    Answer: (A) Insects

37. "Golden Rice" is rich in:

    (A) Vitamin C (B) Vitamin A (C) Vitamin D (D) Vitamin K

    Answer: (B) Vitamin A

38. The interaction between a Cuckoo and a Crow is:

    (A) Predation (B) Commensalism (C) Brood Parasitism (D) Mutualism

    Answer: (C) Brood Parasitism

39. Lichens are an example of:

    (A) Parasitism (B) Mutualism (C) Competition (D) Amensalism

    Answer: (B) Mutualism

40. The pyramid of energy is always:

    (A) Upright (B) Inverted (C) Spindle-shaped (D) Both A and B

    Answer: (A) Upright

41. The reservoir for the Phosphorus cycle is:

    (A) Atmosphere (B) Rocks (C) Ocean (D) Living organisms

    Answer: (B) Rocks

42. Secondary succession takes place on:

    (A) Bare rock (B) Newly cooled lava (C) Abandoned farmland (D) Newly created pond

    Answer: (C) Abandoned farmland

43. The "Evil Quartet" is a term related to:

    (A) Population growth (B) Biodiversity loss (C) Global warming (D) Ozone depletion

    Answer: (B) Biodiversity loss

44. Which of the following is an "Ex-situ" conservation method?

    (A) National Park (B) Wildlife Sanctuary (C) Seed Bank (D) Biosphere Reserve

    Answer: (C) Seed Bank

45. The "Earth Summit" (1992) was held in:

    (A) Johannesburg (B) Rio de Janeiro (C) Stockholm (D) Kyoto

    Answer: (B) Rio de Janeiro

46. What is the range of human hearing?

    (A) 20 Hz - 20,000 Hz (B) 10 Hz - 10,000 Hz (C) 50 Hz - 50,000 Hz (D) 5 Hz - 500 Hz

    Answer: (A) 20 Hz - 20,000 Hz

47. "Eutrophication" is often seen in:

    (A) Deserts (B) Fresh water lakes (C) Mountains (D) Oceans

    Answer: (B) Fresh water lakes

48. The thickness of Ozone is measured in:

    (A) Decibels (B) Dobson Units (C) Pascals (D) Nanometers

    Answer: (B) Dobson Units

49. Kyoto Protocol is associated with:

    (A) Ozone depletion (B) Greenhouse gases (C) Water pollution (D) Biodiversity

    Answer: (B) Greenhouse gases

50. The process of separation and purification of expressed protein before marketing is:

    (A) Upstream processing (B) Downstream processing (C) Bioprocessing (D) Post-production

    Answer: (B) Downstream processing