CBSE Class 12 Biology Question Paper 2020 Set D Solved

Access and download CBSE Class 12 Biology Question Paper 2020 Set D Solved, 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 Question Paper 2020 Set D Solved to begin your self-assessment today.

Biology Class 12 Question Paper PDF with Solutions

SECTION A
 
1 How can an alien piece of DNA made to multiply in a host cell? 
 
2 If adenine constitutes 30% of an isolated DNA fragment, then what is the expected % of the base cytosine in it?
 
3 What is the relationship between egret and grazing cattle? Why?
 
OR
 
How is competition avoided in Nature? Give example.
 
4 A male honeybee has 16 chromosomes whereas its female has 32 chromosomes. Give one reason. 
 
5 Name the vector of Chikungunya disease. 
 
SECTION B
 
6 How does geitonogamy differ from xenogamy in plants? 
 
7 How are transgenic animals made useful in chemical safety testing and studying diseases? 
 
8 What is meant by germplasm Collection? Describe its significance in plant breeding programmes.
 
OR
 
Name two alcoholic drinks produced in each of the following ways. (i) by distillation and (ii) without distillation.
 
9 A person shows unwelcome immunogenic reactions while exposed to certain substances. (a) Name this condition. (b) What common term is given to the substances responsible for this condition? (c) Name the cells and the chemical substances released which cause such reactions.
 
10 Monocistronic structural genes in eukaryotes have interrupted coding sequences, Explain. How are they different in prokaryotes?
 
11 Name two types of animals based on their temperature tolerance. 
 
12 Categories the following pairs of examples as convergent or divergent evolutions: (a) Eyes of octopus and mammals. (b) Wings of butterfly and birds. (c) Tuber of sweet potatoes and potato.
(d) Thorns in bougainvillea and tendrils in cucurbits.
 
SECTION C
 
13 How is Biotechnology used to produce Bt cotton? Explain. 
 
14 How does paleontological evidence support evolution of organisms on Earth? 
 
15 Explain free nuclear endosperm development.
 
OR
 
Mention any three differences between spermatogenesis and oogenesis.
 
16 Explain the role of S and P in the experiments conducted by Hershey and chase?
 
OR
 
Explain the mechanism of sex determination in honeybees.
 
17 Describe the three different practices under natural methods of birth control. 
 
18 How do mycorrhizae function as biofertilisers? Explain with example. Name one cyanobacteria that can be used as a biofertiliser.
 
19 How is Agrobacterium tumifaciens used in rDNA technology? Explain ii) What and how are other pathogens are used for the purpose. State two other methods by which host organism can be transformed.
 
20 After a rainy day Shruti found many dragonflies flying over stagnant water. She thinks these flies
come to drink water. i) Is Shruti,s explanation correct? Give your views
ii) Write the significance of your view in organic farming.
 
OR
 
What is biochemical oxygen demand (BOD) test? At what stage of Sewage treatment this test is performed? BOD level of three samples of water labelled as A, B and C are 30 mg/ L, 10mg/L and 500 mg/L respectively. Which sample of water is most polluted?
 
21 a) Taking one example each of habitat loss and fragmentation, explain how the two are responsible for biodiversity loss. b) Explain two different ways of biodiversity conservation.
 
22 What are statins? Name the microorganism that produces this substance. How is it medically important?
 
23 What are the producers in grass land and oceans .How is GPP different from NPP? Why is the productivity in oceans lesser than on land?
 
24 What will be the genotype and phenotype of the offspring if a colour blind man marries a carrier woman? Show the cross.
 
OR
 
How do histones acquire positive charge?
 
SECTION D
 
25 With the help of a cross find out the F2 offsprings produced by crossing homozygous red flower of Snapdragon when crossed with a homozygous white flower. Write the phenotypic and genotypic ratio. State the pattern of inheritance.
 
OR
 
Describe DNA replication and draw the diagram of a replication fork.
 
26 Describe the development of male gametophyte in angiosperms.
 
OR
 
What is placenta? What is its role? Justify Placenta as an endocrine tissue.
 
27 With a flow chart explain the process of decomposition. What factors affect this process?
 
OR
 
In Arcata, the town’s people have created an integrated waste water treatment process within a natural system. A citizen group called FOAM helps in upkeep of this project.
(a) What are the main steps in waste water management done in this way? (b) Ecosan in Kerala and Sri Lanka is also an initiative for water conservation. How?


Please click on below link to downloadCBSE Class 12 Biology Question Paper 2020 Set D Solved

CBSE Class 12 Biology Question Paper 2020 Set D Solved

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 Question Paper 2020 Set D Solved 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 Question Paper 2020 Set D Solved

Regularly practicing CBSE Class 12 Biology Question Paper 2020 Set D Solved 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 Question Paper 2020 Set D Solved 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 Question Paper 2020 Set D Solved?

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

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

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

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