CBSE Class 12 Biology Most Important MCQs Question With Answer

This post contains CBSE Class 12 Biology Most Important MCQs Questions With Answer for Board Exam 2023. All students needs practicing hard to score well in the board exam.

By focusing on the right resources and doing smart work, Class 12 Biology students will be able to achieve their Target scores. In this post, I have provided Important Multiple Choice Questions for CBSE Class 12 Biology board exam 2022-23.

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CBSE Class 12 Biology 2023

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CBSE Class 12 Biology Most Important MCQs Question With Answer
CBSE Class 12 Biology Most Important MCQs Question With Answer

Important Biology  MCQs Questions With Answers

Q1. Asexual reproduction by zoospores is observed in

(a) Penicillium

(b) Hydra

(c) Sponge

(d) Chlamydomonas.

Ans. Chlamydomonas (an alga) reproduces asexually through zoospore formation. These spores are unicellular, naked (without cell wall), motile and flagellated and hence named zoospores (reproductive units).

Q2. Which one of the following part of the plant when put into the soil is likely to produce new offspring?

(a) Part of an internode

(b) A stem cutting with a node

(c) Part of a primary root

(d) A flower

Q3. Which of the following is not an intrauterine device?

(a) Progestasert

(b) Multiload-375

(c) Norplant

(d) Lippes loop

Ans. Progestasert, Multiload 375 and lippes loop are intrauterine devices while norplant is a subcutaneous implant.

Q4. Cleistogamous flowers are self pollinated because

(a) they are bisexual flowers which do not open at all

(b) they are bisexual and open flowers

(c) they are unisexual

(d) their stigma mature before anthers dehisce.

Q5. Which one of the following is not found in a female gametophyte of an angiosperm?

(a) Germ pore

(b) Synergids

(c) Filiform apparatus

(d) Central cell

Q6 .The theory of evolution supported by the experiment conducted by Louis Pasteur is

(a) Spontaneous generation theory

(b) Life comes only from pre-existing life

(c) Abiogenesis of life

(d) Big bang theory.

Ans.  Louis Pasteur disproved spontaneous generation theory and proved biogenesis, i.e., life comes from pre-existing life

Q7. Louis Pasteur demonstrated that

(a) early life came from outer space

(b) non-living chemicals produced living molecules

(c) life comes from pre-existing life

(d) life originated spontaneously.

Ans. Louis Pasteur disproved spontaneous generation theory and proved biogenesis, i.e., life comes from pre-existing life.

Q8. The diagnostic test that confirms typhoid in humans is


(b) Widal

(c) MRI

(d) Amniocentesis

Q9. Blue revolution refers to

(a) construction of water dams for conservation of water

(b) production of fish in large quantities

(c) sewage treatment

(d) controlling algal bloom.

Ans. Blue revolution is used for production of fish.

Q10. The practice of mating unrelated animals within the same breed but with no common ancestor on either side of the pedigree for 4-6 generations is known as

(a) outbreeding

(b) out-crossing

(c) cross-breeding

(d) inbreeding.

Q11. Mating of a superior male of a breed of a cattle to a superior female of another breed is called

(a) inbreeding

(b) out-crossing

(c) outbreeding

(d) cross-breeding

Q12. Large holes in “Swiss Cheese” are due to

(a) Propionibacterium shermanii

(b) Saccharomyces cerevisiae

(c) Penicillium chrysogenum

(d) Acetobacter aceti.

Ans.  Large holes in ‘Swiss Cheese’ are due to CO2 produced by bacterium called Propionibacterium shermanii during the process of fermentation.

Q13. The bioactive molecule used as an immunosuppressive agent during organ transplant is

(a) tetracyclin

(b) cyclosporin A

(c) statin

(d) streptomycin. 

Ans.  Cyclosporin A has immunosuppressive properties and inhibits T cell activation thereby preventing rejection reactions in organ transplant.

Q14. Nematode specific genes were introduced into tobacco host plant by using the vector

(a) plasmid

(b) bacteriophage

(c) pBR 322

(d) Agrobacterium

Ans. Using Agrobacterium vectors, nematode specific genes were introduced into tobacco plant.

Q15. Which one of the following is not the product of transgenic experiments?

(a) Pest resistant crop variety

(b) High nutritional value in grains

(c) Production of insulin by rDNA technique

(d) Drought resistant crops

Q16. It is observed that the species diversity decreases as we

(a) move away from equator to poles

(b) move towards equator from poles

(c) move along the equator

(d) move from deserts to rainforests

Q17. Species-area relationship is represented on a log scale as

(a) hyperbola

(b) rectangular hyperbola

(c) linear

(d) inverted.

Q18. CNG is preferred as a fuel over diesel for public transport because

(i) it is cost effective

(ii) it burns almost completely

(iii) it can be recycled

(iv) it burns only partially.

Choose the correct combination.

(a) (i) + (ii)

(b) (i) + (iii)

(c) (ii) + (iii)

(d) (iii) + (iv)

Q19. Exine is dry, smooth and non sticky in

(a) wind pollinated plants

(b) insect pollinated plants

(c) both (a) and (b)

(d) none of these.

Ans. Exine is the outer thick, highly resistant layer of pollen grain. In wind pollinated plants, exine is mostly smooth, dry and non-sticky whereas in insect pollinated plants, it is mostly spiny and sticky.

Q20. Where is an antigen binding site present on an antibody molecule?

(a) Constant region of both heavy chains

(b) Constant region of both light chains

(c) Variable regions of heavy and light chains

(d) None of these

Ans. The antigen binding sites (paratopes) are present on the variable regions of both the heavy chains and light chains of an antibody molecule. The antigen binding sites bind to specific antigens in a lock and key pattern, forming an antigenantibody complex.

Q21.Murrah and Nagpuri are breeds of

(a) buffalo

(b) cow

(c) hen

(d) sheep.

Ans. Buffaloes are restricted to some part of Asia only. In India six breeds occur, Jaffarabadi, Mehsana, Murrah, Nagpuri, Nili and Surti. All are good milk producers.

Q22. The mechanical measure for population control includes

(a) condom

(b) diaphragm

(c) IUD

(d) all of these.

Ans. Mechanical contraceptive methods include barriers (condoms, femidoms, diaphragms, cervical caps, etc. and IUCDs

Q23. Refer to the given figure and identify structure X in cockroach.

(a) Testis

(b) Ovary

(c) Sperms

(d) Egg

Q24. Which one is a true statement regarding DNA polymerase used in PCR?

(a) It is used to ligate introduced DNA in recipient cells.

(b) It serves as a selectable marker.

(c) It is isolated from a virus.

(d) It remains active at high temperature.

Ans. In PCR (Polymerase Chain Reaction) DNA polymerase such as Taq polymerase is used which is thermostable and can withstand upto 94°C of temperature.

Q25. Which of the following has the longest life span?

(a) Banyan tree

(b) Tortoise

(c) Parrot

(d) Elephant

Q26. Progesterone pill helps in preventing pregnancy by not allowing

(a) ova formation

(b) fertilisation

(c) implantation

(d) none of these.

Q27. Which of the following is incorrectly paired?

(a) Wheat – Himgiri

(b) Milch breed – Sahiwal

(c) Rice – Ratna

(d) Pusa Komal – Brassica

Q28.Which one of the following is not used as biofertiliser?

(a) Bacillus thuringiensis

(b) Anabaena

(c) Nostoc

(d) Rhizobium

Q29. Which of the following statements is wrong?

(a) Sertoli cells provide nutrition to the developing male germ cells.

(b) Leydig cells synthesise and secrete androgens.

(c) Secretions of the acrosome helps the sperm to enter into the cytoplasm of the ovum.

(d) Secondary spermatocytes are diploid.

Q30. Which among the following are not biofortified crops released by IARI, New Delhi?

(a) Vitamin-A enriched carrot, spinach, pumpkin

(b) Vitamin-C enriched bittergourd, bathua, mustard, tomato

(c) Iron and calcium enriched spinach

(d) Co. 421 of sugarcane and Sonora-64 of wheat

Q31. Select the correct statement regarding activated sludge formed during secondary sewage treatment.

(a) A small part of it is rapidly pumped back from sedimentation to aeration tank.

(b) It absorbs pathogenic bacteria present in waste water while sinking to the bottom of the settling tank.

(c) A major part of it is anaerobically digested.

(d) Both (a) and (c)

Q32. Which out of the following groups represent autoimmune disorders?

(a) SCID and diphtheria

(b) Diabetes mellitus (type I) and rheumatic fever

(c) AIDS and cholera

(d) Hepatitis and leukaemia

Q33. Shakti, Rattan and Protina (varieties of maize) are rich in

(a) lysine

(b) glycine

(c) fats

(d) carbohydrates.

Q34. Which one of the following characteristics is generally not preferred for a cloning vector?

(a) An origin of replication

(b) An antibiotic resistance marker

(c) Multiple restriction sites

(d) A high copy number

Q35. Adenosine deaminase deficiency can be permanently cured by which of the following methods?

(a) Bone marrow transplantation

(b) Enzyme replacement therapy

(c) Gene therapy at early embryonic stages

(d) All of these

Q36. The second stage of hydrosere is occupied by plants like

(a) Azolla

(b) Typha

(c) Carex

(d) Vallisneria.

Q37.Select the correct match.

(a) Integrated : Ramesh Chandra Dagar farming

(b) Integrated waste : Ahmed Khan water treatment

(c) Solid waste : Ramesh Chandra Dagar management

(d) E-waste : Chandi Prasad Bhatt management

Q38. Androgens are synthesised by

(a) Sertoli cells

(b) Leydig cells

(c) Seminal vesicles

(d) Bulbourethral gland.

Q39. A procedure that finds use in testing for genetic disorders, but is also misused for female feticide is

(a) lactational amenorrhea

(b) amniocentesis

(c) artificial insemination

(d) parturition.

Ans. Amniocentesis is a disorder detection test based on chromosomal pattern, but is being misused to determine the sex of the fetus and kill the normal female fetuses. Therefore, it is legally banned to avoid female feticide.

Q40. Which type of immune response is responsible for the rejection of tissues /organs in the patient’s body post transplantation?

(a) Auto-immune response

(b) Humoral immune response

(c) Physiological immune response

(d) Cell-mediated immune response

Ans. Cell mediated immune response is responsible for the rejection of tissue/organs in the patient’s body part transplantation

Q41. The filiform apparatus is present in

(a) synergids

(b) egg cell

(c) antipodals

(d) secondary nucleus.

Ans. The synergids have special cellular thickenings at the micropylar tip called filiform apparatus, which play an important role in guiding the pollen tube into the synergid.

Q42. The term ‘molecular scissors’ refers to

(a) recombinant DNA

(b) restriction enzymes

(c) Taq polymerase

(d) palindromic nucleotide sequences.

Ans. The restriction endonuclease enzyme inspects the length of a DNA sequence. Once it recognises specific sequence, it binds to the DNA and cuts each of the two strands of the double helix at specific points in their sugar phosphate back bone. Restriction endonuclease enzymes are also known as molecular scissors or biological scissors or chemical knives or chemical scalpels.

Q43. The genetic material of HIV is

(a) dsDNA

(b) dsRNA

(c) ssDNA

(d) ssRNA.

Ans. HIV which causes AIDS is a retrovirus that contains single stranded RNA (ssRNA) as its genetic material.

Q44. After completion of the biosynthetic stage in the bioreactors, the product undergoes separation and purification processes, collectively termed as

(a) transformation

(b) electrophoresis

(c) downstream processing

(d) upstream processing.

Q45. Even in absence of pollinating agents seedsetting is assured in

(a) Commelina

(b) Zostera

(c) Salvia

(d) Fig.

Ans. Commelina produces two types of flower- chasmogamous flowers which are similar to flowers of other species with exposed anthers and stigma, and cleistogamous flowers which do not open at all. In such flowers, the anthers and stigma lie close to each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous as there is no chance of cross-pollen landing on the stigma. Cleistogamous flowers assure seedsetting even in the absence of pollinators.

Q46.Lower narrow end of uterus is called

(a) urethra

(b) cervix

(c) clitoris

(d) vulva.

Q47. Which of the following is not used as a biopesticide?

(a) Trichoderma harzianum

(b) Nucleopolyhedrovirus

(c) Xanthomonas campestris

(d) Bacillus thuringiensis

Q48. Early detection of a disease is possible by

(a) PCR

(b) gene therapy

(c) recombinant DNA technology and ELISA

(d) both (a) and (c).

Ans. : For effective treatment of a disease, early diagnosis and understanding its pathophysiology is very important. Using conventional methods of diagnosis (serum and urine analysis, etc.), early detection is not possible. Recombinant DNA technology, Polymerase Chain Reaction (PCR)  nd Enzyme Linked Immuno-sorbent Assay (ELISA) are some of the techniques that serve the purpose of early diagnosis.

Q49. A genetic disorder can be cured through

(a) rDNA technology

(b) embryo transfer

(c) gene therapy

(d) all of these.

Ans. Gene therapy is a collection of methods, that allows correction of a gene defect that has been diagonsed in a child embryo.

Q50. If a plasmid vector is digested with EcoRI at a single site, then

(a) one sticky end will be produced

(b) two sticky ends will be produced

(c) four sticky ends will be produced

(d) six sticky ends will be produced.

Ans. Plasmid is a circular DNA, if it is digested at a single site, one fragment will be produced with two sticky ends.

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