Class 12 Biology Important Questions for Board Exam 2025 (New)

Biology subject plays a major role not only in class 12th but also in the later years, especially for those students who intend to opt for the medical domain. For this, students must have a solid grasp on the fundamentals of the Biology subject. This can be showcased by scoring good marks in the biology board exam. For this, students must solve the mock tests and expected board exam papers for the upcoming board exam. So, we have provided the expected board exam paper based on the latest curriculum.

Class 12 Biology Important Questions for Board Exam 2025

The expected Class 12 Biology board paper 2025 contains the same number of questions and the same mark distribution as in the real exam paper. The questions have been carefully created by analyzing the past year’s papers and the latest changes. It is likely that many questions might be repeated in the actual biology board exam. So, students must go through each and every question (and its solution) given below in the expected board exam paper.

Class 12 Biology Board Paper 2025

The CBSE Class 12 Biology Examination will be held on March 19, 2025. Thus it is important that we maximize our Class 12 Biology exam performance right now by solving the expected board exam paper. In order to be ready to respond to questions in the test room, students should practice as much as they can using the Sample Class 12 Biology Board Paper 2025.

For the convenience of class 12 candidates, our Adda247 Expert faculty prepares the Expected Class 12 Biology Board Paper 2025, which is based on the proper CBSE Class 12 Exam pattern. Those who intend to take the Class 12 Biology Board Examination in 2025 must take the expected Class 12 Biology Board Paper 2025 and match their answers with the solution key given in the article.

Class 12 Biology Board Paper 2025 Revision

Biology Class 12 Board Expected Question Paper Structure

Like the official CBSE Class 12 Biology sample paper, the Adda247 Class 12 Biology Board Paper 2025 has five sections and a maximum score of 70. See the mark distribution for the Class 12 Biology Board Exam 2025 below.

• All questions are compulsory.
• The question paper has five sections and 33 questions. All questions are compulsory.
• Section–A has 16 questions of 1 mark each; Section–B has 5 questions of 2 marks each;
• Section– C has 7 questions of 3 marks each; Section– D has 2 case-based questions of 4 marks each; and Section– E has 3 questions of 5 marks each.
• There is no overall choice. However, internal choices have been provided in some questions.
• A student has to attempt only one of the alternatives in such questions.
• Wherever necessary, neat and properly labelled diagrams should be drawn.

Class 12 Biology Official Additional Paper

The CBSE has released the official additional paper for better understanding of the types of questions that may be asked in the exam. So, students must go through the official additional paper questions and their solutions that has been provided in the following video in a detailed manner.

Class 12 Biology Important Questions for Board Exam 2025- Section A

1. Which of the following divalent cation is used to increase the efficiency of DNA so that it easily enters the bacterium through the pores present in its walls?
(a) Magnesium
(b) Barium
(c) Calcium
(d) All of the above

Ans. (c) In order to force bacteria to take up the plasmid, the bacterial cells must first be made ‘competent’ to take up DNA. This is done by treating them with a specific concentration of a divalent cation, such as calcium,

2. Which among the following are the major producers in a terrestrial ecosystem?
(a) Herbaceous plant
(b) Woody plants
(c) Algae and phytoplankton
(d) None of the above

 Ans. (c ) woody plants such as trees and shrubs are the main producers of the terrestrial ecosystem as they comprise the vegetation in terrestrial ecosystems.

3. In humans, fertilization takes place in which out of following part of the female reproductive system?
(a) Uterus
(b) Oviduct
(c) Cervix
(d) All of the above

Ans. (b)Oviduct

4. Vertebrae heart and brains are examples of.
(a) Analogous organs
(b) Homologous organs
(c) Both (a) and (b)
(d) None of the above

Ans. (b) Homologous organs are those organs in different organisms which appear different but are similar in basic anatomical structure and have diverged from a common ancestor. Vertebrate hearts and vertebrate brains are examples of homologous structures.

5. What is the mode of action of oral pills?
(a) They inhibit ovulation
(b) They inhibit implantation
(c) Alter the quality of cervical mucus so as to retard the entry of sperms
(d) All of the above

Ans. (d) oral contraceptives block the ovulation, that is prevent releasing of eggs from the ovary. They alter the mucus in the cervix and prevent the entry of sperms.

6. When a flower can be divided into two equal radial halves in any radial plane passing through the centre then it is said to be.
(a) Zygomorphic
(b) Actinomorphic
(c) Asymmetric
(d) None of the above

Ans. (b) actinomorphic flowers have radial symmetry, such type of flowers are found in mustard, datura, chilli.

7. Which of the following is used by organic farmers to control aphids in a crop field?
(a) Dragonflies
(b) Ladybird
(c) Bacillus thuringiensis
(d) Both (a) and (b)

Ans. (d) Ladybird the beetle with red and black markings and Dragonfliesis very useful in the control of aphids in a crop field.

8. Who of the following proposed the central dogma in molecular biology?
(a) Schleiden and Schwann
(b) Francis Crick
(c) Puneet
(d) Miescher

Ans. (b)Francis Crick

9. Which of the following is/are ringworms?
(a) Microsporum
(b) Trichophyton
(c) Epidermophyton
(d) All of the above

Ans. (d) Many fungi belonging to the genera Microsporum, Trichophyton and Epidermophyton are responsible for ringworms which is one of the most common infectious diseases in man.

10. Which of the following shows adaptive radiation?
(a) Moth
(b) Finches
(c) Penguin
(d) Dolphin

Ans. (b)Finches

11. Which of the following is also called as brewer’s yeast?
(a) Saccharomyces cerevisiae
(b) Lactobacillus
(c) Clostridium butylicum
(d) None of the above

Ans. (a) yeast Saccharomyces cerevisiae is used for bread-making and commonly called brewer’s yeast, is used for fermenting malted cereals and fruit juices, to produce ethanol.

12. A blind approach of simply sequencing the whole set of genome containing all the coding and non-coding sequence is called.
(a) EST
(b) Sequence annotation
(c) SNP
(d) None of the above

Ans. (b)

Questions No. 13 to 16 consist of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below:
A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true and R is not the correct explanation of A.
C. A is true but R is false.
D. A is False but R is true

13. Assertion: Indian Government allow MTPs under some restricted conditions.
Reason: Such restrictions are all the more important to check indiscriminate
and illegal female foeticides which are reported to be high in India.

Ans. (a)

14. Assertion: It is now proven that DNA replicates semi conservatively.

Reason: It was shown first in Clostridium and subsequently in higher organisms

Ans. (c) It was shown first in Escherichia coli and subsequently in higher organisms.

15. Assertion: Seed is the basis of our agriculture.
Reason: Dehydration and dormancy of mature seeds are crucial for storage of seeds which can be used as food throughout the year and also to raise crop in the next season.

Ans. (a)

16. Assertion: If any protein-encoding gene is expressed in a heterologous host, it is called a recombinant protein.
Reason: Bioreactors are vessels in which raw materials are biologically converted into specific products, individual enzymes, etc., using microbial plant, animal or human cells.

Ans. (a)

Class 12 Biology Important Questions for Board Exam 2024: Section B

17. Name any two vertebrate body parts that are homologous to human fore- limbs.18. Mention the attributes which a population has but not an individual organism.
19. Can we detect a disease before the appearance of its symptoms?
20. What is vaccine? Give an example of a vaccine produced by recombinant technology.

21. Describe stratification by giving an example.

Class 12 Biology Important Questions for Board Exam 2024: Section C

22. What is the difference between microsporogenesis and megasporogenesis. Name the type of cell division that takes place during this process. What are the structures that are formed at the end of these processes?

23. Given below is a flow chart, study it carefully and name the hormones that are involved at each stage in a human female.

24. (a) Draw the structure of the initiator tRNA adaptor molecule.

(b) Why is tRNA called an adaptor molecule

25. Why is the primary immune response is of slow intensity than secondary immune response. Justify the statement.

26. Explain how hnRNA becomes the mRNA? 3
27. DNA cannot pass through cell membranes, name and explain a technique by
it can be forced to pass into a bacterial cell.

28. Plants bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO). GM plants have been useful in many ways. Give at least five examples in support of the statement.

Class 12 Biology Important Questions for Board Exam 2024: Section D

Q.no 29 and 30 are case-based questions. Each question has subparts with internal choice in one subpart.

29. In living cells, such as E. coli, the process of replication requires a set of catalysts (enzymes). Many additional enzymes are required to complete the process of replication with high degree of accuracy. For long DNA molecules,since the two strands of DNA cannot be separated in its entire length (due to very high energy requirement), the replication occur within a small opening of the DNA helix. Answer the questions that follow:

(a) Name the small opening of the DNA within which the process of replication occurs. What is the reason behind the creation of this small opening?
(b) Name the enzyme that plays an important role in the polymerisation reaction during the replication process.
(c) What is the polarity of the template DNA ?

OR

(c)What would happen if there is a failure in cell division after DNA replication?

30. The size of the population tells us a lot about its status in the habitat. Whatever ecological processes we wish to investigate in a population, be it the outcome of competition with another species, the impact of a predator or the effect of a pesticide application, we always evaluate them in terms of any change in the population size. Answer the questions that follow:

(a) How would you represent a declining population with the help of an age pyramid?
(b) An area is facing high mortality rate and emigration rate, what be the effect of population size in this case?
(c) List two factors that are important for unimpeded growth of a population?

OR

(c)In a pond were 20 frogs last year, reproduction added 8 new frogs to that pond. What will be the birth rate?

Class 12 Biology Important Questions for Board Exam 2024: Section E

Section E

31. Contraceptives also can be consumed orally. Mention some orally taken contraceptives. Explain their mode of action? In what dose are the females advised to take them?

OR

What do you understand by MTP? Mention it’s safety concern and in what cases has the government of India allowed it in our country?

32. What is recombination? Mention its applications with reference to genetic engineering.

OR

Explain the contributions of Morgan and Sturtevant in the area of genetics.

33. (a) What is the difference between unambiguous and degenerate genetic codes?
(b) What is significance of Severo Ochoa enzyme?

OR

Provide any five silent feature of human genome.

Class 12 Biology Important Questions for Board Exam 2024 With Solutions

We also provide full solutions for the Class 12 Biology important Question for Board Exam Paper 2024. Students can examine their grades after completing the expected Class 12 Biology board paper 2024. We have provided another expected board question paper 2024 with solutions so that students can practice a wide range of questions that will aid in scoring better marks in the board exam.

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