CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved

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Previous Year Question Papers for Class 12 Biology

Access comprehensive previous year question papers for Class 12 Biology using the CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved. Designed to align with the 2026-27 CBSE academic guidelines, these solved papers help students assess their exam readiness and understand official marking schemes.

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Navigate directly to the solved Biology question papers using the digital viewer below. Each practice set includes detailed solutions, allowing students to instantly cross-check their work and identify areas requiring further revision.

SECTION A
Note : Choose the correct option from the choices given in each of the following questions :
 
1. Introduction of an alien DNA into a plant host cell is achieved by making them
 
(A) Competent with bivalent ions
 
(B) Using microinjections
 
(C) Using gene gun
 
(D) Using lysozymes and chitinase
 
2. One of the ex situ conservation methods for endangered species is
 
(A) Biosphere reserves
 
(B) National parks
 
(C) Cryopreservation
 
(D) Wildlife sanctuaries
OR
Ozone gas is continuously formed in the stratosphere by 
 
(A) Action of UV rays on nascent oxygen
 
(B) Reaction of oxygen with water vapour
 
(C) Action of UV rays on molecular oxygen
 
(D) Action of UV rays on water vapour
 
3. Intense lactation in mothers acts as a natural contraceptive due to the
 
(A) Suppression of gonadotropins
 
(B) Hypersecretion of gonadotropins
 
(C) Suppression of gametic transport
 
(D) Suppression of fertilization
 
4. The principle of vaccination is based on the property of
 
(A) Specificity
 
(B) Diversity
 
(C) Memory
 
(D) Discrimination between ‘self ’ and ‘non-self ’
OR
Opioids act as
 
(A) Depressants
 
(B) Pain killers
 
(C) Euphoria providers
 
(D) Stimulants
 
5. Nematode specific genes were introduced into the tobacco host plant by using the vector
 
(A) Plasmid
 
(B) Bacteriophage
 
(C) pBR 322
 
(D) Agrobacterium
 
SECTION B
 
6. Spirulina is a rich source of proteins. Mention the two ways by which large scale culturing of these microbes is possible.
 
7. How does EcoRI specifically act on DNA molecule ? Explain.
 
8. (a) Explain the cause responsible in a human to have sex chromosomes as ‘XXY’ instead of ‘XX’ or ‘XY’.
 
    (b) List any two ways such individuals are different from the normal being.
Please click on below link to download CBSE Class 12 Biology Boards 2020 Question Paper Solved Set C.

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Practice Exam Question Papers for Class 12 Biology CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved

Previous Year Question Papers: Class 12 Biology

Access structured past examination sets for Class 12 Biology. Solving the CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved provided above helps students understand actual exam difficulty levels, question formats, and topic distributions for both descriptive and objective sections.

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Reviewing official papers clarifies the exact marking scheme and structural layout established by the CBSE, enabling students to structure answers for maximum score potential.

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FAQs

Where can I download the official PDF for CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved?

The CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved is available for download on StudiesToday.com. It includes complete set with all sections so that Class 12 students can practice with the exact same paper that came in the CBSE exams.

Are the solutions for CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved based on the official CBSE marking scheme?

Yes, the solutions for CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved are prepared by subject matter experts as per official marking scheme. Class 12 students will understand the structure of answers and 'step-marks' methodology Biology.

How does solving CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved help in preparing for the 2026 exams?

Solving previous year papers like CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved is important to understand repeat themes and question difficulty levels of Biology. It helps Class 12 students to test their time management skills too.

Can I access CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved in different languages?

Yes, where applicable, CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved is available in both English and Hindi mediums. All students from Class 12 can access Biology study material in their preferred language.

Is there a charge to download the CBSE Class 12 Biology solved papers?

No, all previous year question papers on StudiesToday, including CBSE Class 12 Biology Boards 2020 Question Paper Set 03 Solved, are provided free of charge in mobile-friendly PDF.