CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A

Access and download CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A, carefully designed as per the latest 2025-26 examination guidelines issued by CBSE, NCERT, and KVS. These Class 12 Biology previous year question papers include detailed solutions, helping students to assess their performance and identify and improve key areas before the final exams.

Solved Biology Question Papers for Class 12

Practicing these Class 12 Biology question papers is the best way to understand the actual exam pattern and marking scheme. By solving these papers under timed conditions, Class 12 students can improve their speed and accuracy. Download the full CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A to begin your self-assessment today.

Biology Class 12 Question Paper PDF with Solutions

SECTION A
1. Meselson and Stahl carried out centrifugation in CsCl2 density gradient to separate :
(A) DNA from RNA
(B) DNA from protein
(C) The normal DNA from 15N-DNA
(D) DNA from tRNA
 
2. Self-pollination is fully ensured if 1
(A) the flower is bisexual.
(B) the style is longer than the filament.
(C) the flower is cleistogamous.
(D) the time of pistil and anther maturity is different.
OR
Zoospores are the reproductive units to carry asexual reproduction in 
(A) Chlamydomonas
(B) Spirogyra
(C) Yeast
(D) Rhizopus
 
3. Micropropagation can be achieved by 
(A) Self-pollination
(B) Asexual reproduction
(C) Tissue culture
(D) Vegetative propagation
OR
The microbes commonly used in kitchens are 
(A) Lactobacillus and Yeast
(B) Penicillium and Yeast
(C) Microspora and E. coli
(D) Rhizopus and Lactobacillus
 
4. The main barrier that prevents the entry of micro-organisms into our body is
(A) Antibodies
(B) Macrophages
(C) Monocytes
(D) Skin
 
5. Nematode specific genes were introduced into the tobacco host plant using a vector
(A) pBR 322
(B) Plasmid
(C) Bacteriophage
(D) Agrobacterium
 
6. Given below is one of the strands of a DNA segment :
           TACGTACGTACGTACG
3' _________________________________5'
(a) Write its complementary strand.
(b) Write a possible RNA strand that can be transcribed from the above DNA molecule formed.
 
7. Wings of birds and wings of butterflies contribute to locomotion. Explain the type of evolution such organs are a result of.
 
8. It is often observed that the chances of a person suffering from measles in his or her lifetime are low if he or she has suffered from the disease in their early childhood. Justify the statement.
 
9. List the three hormones produced in women only during pregnancy.
What happens to the levels of estrogen and progesterone during pregnancy ?
 
10. A student on a field trip suddenly felt breathlessness and started to sneeze very badly. Name this response and explain what it is due to.
 
11. With the help of a suitable example, explain how cross-breeding is carried out in developing a new breed in animals.
 
12. Name the genus of baculovirus that acts as a biological control agent in spite of being a pathogen. Justify by giving three reasons that make it an excellent candidate for the job.
OR
‘‘Micro-organisms play an important role for the biological treatment of sewage.’’ Justify.
Please click on below link to download CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A.

CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A

To understand the types of questions asked in past examinations, it is very important for Class 12 students to solve the CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A provided above. You can easily download these past papers for Class 12 Biology in PDF format for the last 10 years. By practicing these actual exam questions you will gain an understanding of the difficulty level and the variety of topics covered over the years. By solving these Previous Year Papers (PYPs) you will understand both descriptive and MCQ questions in your final tests.

Importance of solving CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A

Regularly practicing CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A is the best way to improve your score in Class 12 Biology. These papers will give you details of the marking scheme and the paper structure used by the CBSE. By regularly attempting these under actual exam conditions at home, you can slowly improve your time management skills, which will help you to complete your Biology paper within the allowed duration.

Benefits of downloading CBSE Class 12 Question Papers

Having the CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A in PDF format allows you to revise key concepts anywhere, even without an internet connection. These sets are a reliable tool to practice numerical problems and understand the correct approach to all types of answers. After solving the questions, you should compare your work with the solutions provided by our teachers. Along with these papers, students should always solve the Class 12 Biology Sample Papers and MCQ tests on studiestoday.com for a complete revision.

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

The CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A 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 Solved Set A based on the official CBSE marking scheme?

Yes, the solutions for CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A 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 Solved Set A help in preparing for the 2026 exams?

Solving previous year papers like CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A 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 Solved Set A in different languages?

Yes, where applicable, CBSE Class 12 Biology Boards 2020 Question Paper Solved Set A 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 Solved Set A, are provided free of charge in mobile-friendly PDF.