Best Class 12 Biology MCQs with Answers for Pre Board Exam 2026

Best Biology MCQs with Answers for Pre Board Exam 2026: CBSE Board Pre Board Exam 2026 is around the corner, and now students should start practising MCQs for biology to check their chapter-wise preparation.  In this article, we have compiled some important MCQ questions that are expected in the exam. These CBSE Class 12 Biology MCQs with answers cover key concepts that are commonly tested in both pre-boards and 2026 boards. Practising these top multiple-choice questions from the Class 12 Biology Syllabus will increase conceptual clarity, accuracy, and confidence ahead of the exam.

Best Biology MCQs with Answers for Pre Board Exam 2026

The Class 12 Biology syllabus has a total of 14 chapters. Biology Multiple-choice questions (MCQs) are intended to help students grasp the idea of each chapter properly. They are useful for revising and understanding things efficiently. These class 12th biology multiple-choice questions, which include in-textbook questions and central concepts, help students assess their level of preparedness for the CBSE board exams.

Most Important Class 12 Biology MCQs with Answers

These 15 MCQ set is suitable for last-minute revision and strategic planning to excel in the CBSE Class 12 Biology Pre Board Exam 2026.

1. A person having genotype IA IB would show the blood group as AB. This is because of
(a) pleiotropy
(b) co-dominance
(c) segregation
(d) incomplete dominance.
Answer:
(b) co-dominance

2. A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents ?
(a) TT and Tt
(b) Tt and Tt
(c) TT and TT
(d) Tt and It
Answer:
(b) TtandTt

3. Which of the following from the 4 options shows bisexual animals only?
(a) Amoeba, sponge, leech
(b) Sponge, cockroach, Amoeba
(c) Earthworm, sponge, leech
(d) Tapeworm, earthworm, honeybee
Answer:
(c) Earthworm, sponge, leech

4.Meiosis does not occur in
(a) asexually reproducing diploid individuals
(b) sexually reproducing haploid individuals
(c) sexually reproducing diploid individuals
(d) all of these.
Answer:
(a) asexually reproducing diploid individuals

5. Which of the following organisms has the highest number of chromosomes?
(a) Housefly
(b) Butterfly
(c) Ophioglossum
(d) Onion
Answer:
(c) Ophioglossum

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6. If a butterfly has a chromosome number 360 in its meiocyte (2n). What will be the number of chromosomes in its gametes?
(a) 380
(b) 190
(c) 95
(d) 760
Answer:
(b) 190

7. Documented microfossils have been found that are as old as
(a) 2.5 billion years
(b) 3.5 billion years
(c) 1.5 billion years
(d) 2.5 million years.
Answer – (b) 3.5 billion years

8. Who formulated that ‘ontogeny recapitulates phylogeny’ ?
(a) Darwin
(b) Weismann
(c) Haeckel
(d) Lamarck
Answer
(c): Haeckel
Explanation: Ontogeny recapitulates phylogeny, also called biogenetic law, first proposed by Ernst Haeckel in 1866.

9. The presence of gills in the tadpole of a frog indicates that
(a) fishes were amphibious in the past
(b) fishes evolved from frog-like ancestors
(c) frogs will have gills in future
(d) frogs evolved from gilled ancestors
Answer (d): frogs evolved from gilled ancestors
Explanation: The tadpole larva ofa  frog bears gills and lives in water, which proves that frogs have evolved from gilled ancestors

10. The injectable polio vaccine was discovered by
(a) Jonas Salk
(b) Robert Koch
(c) M. Theiler
(d) Louis Pasteur.
Answer (c): M. Theiler
Jonas Salk invented the first safe & effective injectable vaccine for polio (Salk vaccine)

11. All are bacterial diseases except
(a) gonorrhoea
(b) anthrax
(c) swine flu
(d) whooping cough.
Answer
(c): swine flu
Swine flu or swine influenza is a respiratory disease caused by influenza viruses (H1N1).

12. Which of the following can be used as a biocontrol agent in the treatment of plant disease?
(a) Lactobacillus
(b) Trichoderma
(c) Chlorella
(d) Anabaena
Answer: (b) Trichoderma

13. Trichoderma species are free-living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several plant pathogens.
Choose the correct pairs from the following.
(i) Bacillus thuringiensis – Cry protein
(ii) Mycorrhiza — Leguminous plants
(iii) Statins – Inhibit cholestrol synthesis
(iv) Trichoderma polysporum – Cyclosporin A
(a) (i), (ii) and (iii)
(b) (i), (ii), and (iv)
(c) (i), (iii) and (iv)
(d) (ii), (iii) and (iv)
Answer (c): (i), (iii) and (iv)
Explanation: Mycorrhiza is a form of symbiotic association of certain fungi with the roots of higher plants such as oak, pine, peach, etc.

14. Which of the following is not a cloning vector?
(a) pBR322
(b) Cosmid
(c) Yeast artificial chromosome
(d) HindII
Answer (d): HindII
Explanation: Hind II is a restriction enzyme.

15. The direction of energy flow is
(a) producers → carnivores → herbivores → decomposers
(b) producers → herbivores → decomposers → omnivores
(c) producers → herbivores → carnivores → decomposers
(d) producers → carnivores → herbivores → decomposers.
Answer (c): (c) producers → herbivores → carnivores → decomposers
Explanation: The energy flow begins with the producers, who fix solar energy, and then moves on to the herbivores, who feed on the producers. Carnivores devour herbivores, and decomposers decompose them once they die.

We hope the best Class 12 Biology MCQs with answers are helpful for your board exam preparation.