Biology is an important subject that makes it to the Class 12 syllabus on the CBSE Board. It needs a mixture of concept generalisation, correctness, and memorisation of essential facts and processes. This is certainly a scoring subject for a student planning to contest NEET examinations and fare well in board examinations. This article highlights the most important questions in Class 12 Biology and other effective tips to master the subject. The complete guide for you, structured to help you score well in the exam as well as widen your horizon on the subject of biology, will act as your road map to success.
Importance of Emphasis on Key Questions
The CBSE Class 12 Biology exam comprises units such as Reproduction, Genetics and Evolution, Human Health and Disease, Ecology, and Biotechnology. Given the enigma that was put forth before the syllabus was too vast to accommodate in only one class, important topics were selected, which allowed for the efficient preparation of exams. Often-repeated questions are a brilliant way of sharpening the mind on these topics and familiarizing an individual with various forms of questions- short responses, application of their understanding, and long answers, among other types of questions.
Also Read: CBSE Class 12th Science Model Question Paper 2025
Most Expected Questions
1. How is it that the chances of fruit set in a self-pollinated bisexual flower of a plant are far greater than a dioecious plant?
2. Explain giving two examples if there is a relationship between the size and the lifespan of an organism.
3. Why can’t multicellular organisms reproduce by cell division?
4. State the differences between sexual and asexual reproduction. Explain different types of asexual reproduction in unicellular organisms.
5. Rose plants have large flowers but rarely do they produce fruits. On the contrary, the tomato plant produces fruit but has very small flowers. Comment with suitable reasons.
6. How does a chasmogamous bisexual flower prevent self-pollination?
7. Arrange them sequentially according to how they appear in the artificial hybridization programme.
8. Explain the term polyembryony. How is it exploited commercially?
9. What are the functions of a flower?
10. What are the characteristics of wind, water and insect-pollinated flowers?
11. What is the reason for the absence of menstrual cycles during conception or pregnancy?
12. State the role of the epididymis in male fertility.
13. Why does the corpus luteum stay active throughout pregnancy and in the absence of fertilization, is active only for 10-12 days?
14. Explain in detail the difference between the meiotic division of oogenesis and spermatogenesis.
15. Explain the role of pituitary gonadotropins during the follicular and ovulatory phases of the menstrual cycle. Describe the shifts in steroidal secretions.
16. Explain in-vitro fertilization and embryo transfer in brief.
17. What are the important features of an ideal contraceptive?
18. Describe any three assisted reproductive techniques practised to treat infertility.
19. Justify the ban on amniocentesis in our country.
20. What are the advantages and disadvantages of hormonal contraceptives?
21. How is it possible for a child to have blood group O if the parents have blood groups A and B?
22. Why is it that women exceeding 40 years of age have more chances of having a child with Down’s syndrome?
23. Why does sickle-cell anaemia persist in the human population when it is believed that the harmful alleles get eliminated from the population after a certain time?
24. What is aneuploidy? Differentiate between aneuploidy and polyploidy.
25. Why is colour blindness more prominent in males than females?
26. Enumerate the post-transcriptional modifications in a eukaryotic mRNA.
27. What is an operon? Explain an inducible operon.
28. Explain the process of DNA replication.
29. Mention any two functions of the AUG codon.
30. Explain about the dual polymerase present in E.coli.
31. What do you mean by “survival of the fittest”?
32. Creation and presence of variation are directionless, but natural selection is directional as it is in the context of adaptation. Comment.
33. Describe the phenomenon in which two organisms occupying the same geographical area show the same strategies of adaptation.
34. What is the driving force behind divergent evolution? Explain.
35. What are the types of evolution?
36. How is active immunity different from passive immunity?
37. How is a benign tumour different from a malignant tumour?
38. What is the full form of MRI and CT? Where are they used? State the difference between them.
39. What causes adolescents to start using drugs? How can the use of drugs be avoided?
40. What is Ringworm? What are the different types of ringworm?
41. Through the example of the H5N1 virus, explain how diseases are fast spreading due to globalization and increased movement of people.
42. In animal husbandry programmes, how can the success rate of fertilization during artificial insemination be improved?
43. What is natural selection and artificial selection? How does artificial selection influence the evolution process?
44. What are the various steps that a Botanist will undertake to release a new variety of plants?
45. a) How are mutations beneficial for plant breeding? Discuss with an example
b) Explain in brief the technology that made us self-sufficient in food production.
46. What is the significance of floes in the biological treatment of wastewater?
47. For the execution of massive volumes of wastewater rich in organic matter, why is aerobic degradation more important than anaerobic degradation?
48. Discuss the main ideologies crucial in the biological control of diseases and pests.
49. How can microbes be used to decrease the use of chemical fertilizers and pesticides?
50. Describe the kind of food that would have lactic acid bacteria. Mention their useful applications.
51. What is the role of Agrobacterium tumefaciens in plant transformation?
52. What is a bioreactor? Explain different types of bioreactors.
53. Mention any three vector-less methods that are used to introduce recombinant DNA into a competent host cell.
54. What are the properties of a good vector?
55. What is Biotechnology?
56. What do you understand about a recombinant vaccine? Give examples.
57. Why is the line of treatment for a genetic disease different from that of an infectious disease?
58. How can a person suffering from Adenosine Deaminase deficiency be cured?
59. What are the drawbacks of the insulin obtained from slaughtered cows and pigs?
60. Explain five areas where biotechnology has influenced human lives.
61. List and define the characteristics of an individual and population.
62. Describe the different kinds of positive interactions that take place between different species.
63. Name the element that causes salinity in the soil. Explain the state at which soil turns saline.
64. Is the distribution of organisms affected by light? Explain briefly with suitable examples of animals or plants.
65. Why do marine entities lack contractile vacuoles as compared to freshwater entities?
66. The availability of energy is less for entities at higher trophic levels. Why?
67. Why is the number of trophic levels in an ecosystem limited?
68. How does nature favour raising the gross primary productivity while man tends to raise the net primary productivity?
69. Explain the biogeochemical cycle. What is the significance of the reservoir in this cycle? With a reservoir situated in the earth’s crust, give an example of a sedimentary cycle.
70. Explain the structure of the Ecosystem with the flowchart.
71. State how the current occurrence of species extinction is different from the earlier mass extinction.
72. In comparison to other animal groups, why are amphibians more vulnerable to extinction?
73. Explain how species diversity of an area is reduced by the invasion of an alien species.
74. Besides the relationship used by Paul Ehrlich, can you arrive at a scientific explanation to explain the direct association between the stability and diversity of an ecosystem?
75. Write notes on the ‘rivet popper hypothesis’ by Paul Ehrlich.
76. Listing a greenhouse gas, write its possible source of production on a larger scale. What are its harmful effects?
77. How is the bird population affected by DDT?
78. Write notes on electronic waste. Write about the various sources of e-waste and issues associated with its disposal.
79. What are the causes and severe effects of soil salinity and waterlogging in the green revolution?
80. Write three basic characteristics of a modern landfill site. What are the reasons they are used?
Also Read: CBSE Class 12th Sample Question Paper Solution 2025
Benefits of Solving Most Expected Questions Class 12 Biology
Class 12 Biology’s most expected questions allow an intensive way ahead for preparing for the exam to address the vital thrust on punchlines in respective subjects. Such questions also shed light on the expected important points from the syllabus so that adequate time and attention may be awarded to high-yield concepts and chapters.
With such practice, your understanding of the theory may be consolidated, your answer-writing skills might be boosted, and your ability to retain critical details during the exam could be bolstered. More importantly, such questions are often analogous to those inspected in the CBSE examination format, which will enable you to ease into the question pattern as well as the marking scheme with confidence.
Practising these questions strategically is a surefire way to keep your confidence intact. Allow yourself full preparation for both application-based as well as diagram-based questions. Start solving these questions today to equip yourself with what’s required for computation!
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