🦠 12th Zoology Important Three Mark Questions – Public Exam 2025

📚 Ace Your Zoology Exam with Important 3-Mark Questions!
Prepare for the 12th Zoology Public Exam 2025 with chapter-wise important three-mark questions, selected from previous year board exam papers and high-scoring topics. These questions help students revise key concepts and secure easy marks in the exam.

🔹 Chapter-wise 3-mark questions with answers
🔹 Based on Tamil Nadu Board syllabus
🔹 Covers Human Physiology, Genetics, Evolution & Biotechnology
🔹 Essential for quick revision & high scores

12th Zoology Important Three Mark questions

1. What do you mean by regeneration?what are its types?Ln1
2. Name the layers of the wall of uterus?Ln2
3. How does the body organs develop from the primary germ layers?Ln2 Pg24
4. Under what conditions a caesarean section is done?Ln2 Pg26
5. Mention the importance of the position of testes in humans?Ln2 Pg12
6. Draw a neat labelled diagram of Human Ovum?Ln2 Pg19
7. What is cryopreservation?What is its significance?
8. Name the protozoan STI?what are its symptoms?Ln3 Pg38
9. Whan is cervical cancer and write its symptoms?Ln3 Pg38
10. What is infertility?Write down any three causes of infertitility?Ln3 Pg38
11. What is amniocentesis?Briefly describe its statutory ban.is it necessary?Ln3 Pg33
12. Explain vasectomy and Tubectomy?Ln3 Pg35
13. What causes klinefelter’s syndrome?Mention its symptoms?Pg54 Pg55
14. What is karyotyping?What are the applications of karyotyping?Ln 4 Pg53
15. Write the expansion for the following symbols?Ln4 Pg53
16. Explain Down’s syndrome and their symptoms?Ln4 Pg55
17. What causes Erythroblastosis foetalis or Haemolytic disease of the new born?How can it be prevented?Ln4 pg56
18. Differentiate – Template strand and coding strand?Ln5 Pg72
19. Write notes on one gene – one ploypeptide hypothesis?Ln5 62
20. What are the goals of human genome project?Ln5 Pg83
21. Application of DNA fingerprinting?Pg83 Pg86
22. Explain experimental approach to the origin of life with suitable example?Ln6 95
23. Mention salient features of Mutation Theory?Ln6 101
24. Differentiate homologous structures from analogous structures?Ln6 Pg97
25. Write short notes on any one human virus desease that is transmitted by mosquitoes?Ln7 pg115
26. Write any three differences between Active immunity and Passive immunity?Pg118 Pg132
27. AIDS has no cure.But it can be prevented by certain measures.list out any three?Ln8 Pg142
28. Draw the diagram and label the parts of Immunoglobulin?Ln8 Pg137
29. What are the role of Antibodies?Ln8 pg137
30. Explain the Anatomical barriers?Ln8 Pg130
31. What is Bioremediation?what are its types?why is this better than other methods?Ln9 Pg153
32. Distinguish between Somatic cell gene therapy and germline gene therapy?Ln10 Pg161
33. Define stem cell therapy?Ln10 Pg162
34. What is Totipotent,pluripotent and Multi potent?Ln10 Pg163
35. Write short notes on application of PCR?Ln10 Pg165
36. Write any three possible threats of genetically modified organisms?Ln10 Pg170
37. Differentiate j and s shaped curve?Ln11 BB25 Pg189
38. Classify and explain the adaptive traits found in organisms?Ln11 Pg186
39. What are the goals of preparing red book?Ln12 Pg210
40. Write short notes about WWF?Ln12 Pg213
41. Red Data Book –  what do you know about it?Ln12 Pg210
42. Explain the various methods of controlling Air Pollution?Ln13 Pg222
43. Expand a)CFC b)AQI C)PAN Answer(Chlorofluorocarbon,Air Quality Index,Peroxyacetyl nitrate Ln13
44. Explain Mutualism?Ln11 Pg191
45. Tabulate the National Parks of TamilNadu?Ln12Pg211
46. Write about Eutrophication?Ln13 Pg228
47. Compare and contrast bacillary dysentery and Amoebic dysentery?Nill BB18
48. What is plasmotomy?Give example?Pg4
49. Name the primary germ layers and write the organs formed from them?
50. Name the different types of twins and explain how they are produced?
51. Differentiate spermiogenesis and spermatogenesis?BB17 BB19
52. List out various male reproductive glands and mention their secretions?Pg13 Pg13
53. What causes Erythroblastosis foetalis or Haemolytic disease of the new born?How can it be prevented?
54. What is called operons?Pg78 Pg81
55. List out the major gases seems to be found in the primitive earth.BB17 BB17
56. List out chemical alarm signals produced during inflammation.BB18 BB20
57. Differences between R.selected species and k-selected species?Pg176 Pg190
58. Write a note on shifting or jhum cultivation?Pg191 Pg207
59. What is colostrum?write its significance?
60. What is Pedigree analysis?
61. Who disproved Lamarks theory of acquired characters?How
62. Functions of Immunoglobulin?
63. What is Antibiotic resistance?
64. Write the characters of Biome?
65. How can we contribute to promote biodiversity conservation?
66. What is Lyonisation?
67. Compare and contrast the insitu and exsitu conservation.
68. Write the medical waste disposal?

📢 More 12th Zoology Exam Resources:
📘 12th Zoology Two mark questions
📗 12th Zoology Five mark questions
📚 12th Zoology Model Question Papers

🎯 Why Focus on Three-Mark Questions in 12th Zoology?
Two-mark questions are a crucial part of the Zoology public exam, covering definitions, diagrams, short explanations, and key terms. Mastering these ensures full marks in this section.

📚 Chapter-wise 3-Mark Questions Covered:
🔹 Human Physiology – Circulatory System, Nervous System, Excretion
🔹 Genetics & Evolution – DNA Structure, Mendelian Inheritance, Evolution Theories
🔹 Biotechnology & Its Applications – Genetic Engineering, Cloning, DNA Fingerprinting
🔹 Ecology & Environment – Biodiversity, Conservation, Ecosystem Functions

📢 External References for Zoology Exam Preparation:
🔗 12th Zoology Textbook – Tnbooks
🔗 12th Zoology One marks short cuts

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