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Tamil Nadu State Board · CLASS 12th · Zoology

TAMIL NADU STATE BOARD CLASS 12 ZOOLOGY 2026

34 questions from this CLASS 12th Zoology paper. Log in as a CLASS 12th student to view solutions.

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Q1 mcq 1 mark
In which type of Parthenogenesis are only males produced?
  • A. Arrhenotoky
  • B. Thelytoky
  • C. Amphitoky
  • D. Both (a) and (c)

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Q2 mcq 1 mark
Statement I : Castration (or) surgical removal of testis is known as Orchidectomy. Statement II : It leads to difficulty in urination.
  • A. Statement I and Statement II are not correct.
  • B. Statement I and II are correct.
  • C. Statement I is not correct and Statement II is correct.
  • D. Statement I is correct and Statement II is not correct.

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Q3 mcq 1 mark
Select the incorrect action of hormonal contraceptive pills from the following.
  • A. Changes in cervical mucus impairing its ability to allow passage and transport of sperms
  • B. Inhibition of spermatogenesis
  • C. Alteration in uterine endometrium to make it unsuitable for implantation
  • D. Inhibition of ovulation

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Q4 mcq 1 mark
This pedigree symbol represents :
  • A. Male
  • B. Monozygotic twins
  • C. Mating
  • D. Dizygotic twins

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Q5 mcq 1 mark
Hershey and Chase’s experiment with bacteriophage showed that :
  • A. DNA contains radioactive sulphur.
  • B. Protein gets into the bacterial cells.
  • C. Viruses undergo transformation.
  • D. DNA is the genetic material.

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Q6 mcq 1 mark
Find out the wrongly matched pair.
  • A. Y-chromosome - 231 genes
  • B. Chromosome-1 - 2968 genes
  • C. Dystrophin - 2.4 million bases
  • D. Human genome - 300 bases

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Q7 mcq 1 mark
The wings of birds and butterflies is an example of :
  • A. Divergent evolution
  • B. Adaptive radiation
  • C. Variation
  • D. Convergent evolution

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Q8 mcq 1 mark
Which of the following groups of diseases have been controlled by the use of vaccines and by creating awareness among the people ?
  • A. Small pox, amoebiasis, diphtheria, tetanus.
  • B. Small pox, polio, diphtheria, tetanus.
  • C. Small pox, AIDS, diphtheria, tetanus.
  • D. Small pox, common cold, diphtheria, tetanus.

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Q9 mcq 1 mark
Allergy involves :
  • A. IgA
  • B. IgE
  • C. IgM
  • D. IgG

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Q10 mcq 1 mark
The most common substrate used in distilleries for the production of ethanol is __________.
  • A. Molasses
  • B. Soya meal
  • C. Corn meal
  • D. Groundgram

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Q11 mcq 1 mark
Assertion (A) : In nature many organisms produce clones through asexual reproduction. Reason (R) : By this process, genetically identical individuals are produce
  • A. TØÖ ©ØÖ® Põµn® Cµsk® uÁÖ.
  • B. TØÖ \› BÚõÀ Põµn® uÁÖ.
  • C. TØÖ ©ØÖ® Põµn® \› BÚõÀ TØÖ PõµnzvØS \›¯õP ö£õ¸¢uÂÀø».
  • D. TØÖ ©ØÖ® Põµn® Cµsk® \›, TØÖ PõµnzvØS \›¯õP ö£õ¸¢xQÓx.

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Q12 mcq
The relationship between sucker fish and shark is __________.
  • A. Predation
  • B. Competition
  • C. Parasitism
  • D. Commensalism

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Q13 mcq
The term “Niche” was first used by __________.
  • A. John Ray
  • B. Charles Darwin
  • C. Jordon
  • D. Charles Elton

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Q14 mcq
Which one of the following are at higher risk of extinction due to habitat destruction ?
  • A. Amphibians
  • B. Mammals
  • C. Echinoderms
  • D. Birds

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Q15 mcq
__________ is/are an ideal disinfectant for waste water.
  • A. Boiling
  • B. U-V Rays
  • C. Ozonisation
  • D. Chlorination

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Q16 short answer
Define gametogenesis.

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Q17 short answer
What is inhibin ?

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Q18 short answer
Differentiate - Leading strand and Lagging strand.

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Q19 short answer
How does Neanderthal man differ from the Modern man in appearance ?

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Q20 short answer
What is Atavism ?

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Q21 short answer
Draw the structure of Lymph node and label the parts.

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Q22 short answer
Define : Zymology

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Q23 short answer
Differentiate hibernation and aestivation.

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Q24 short answer
What are the gases that cause the Green House Effect ?

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Q25 short answer
Draw Gemmule in sponges and label the parts.

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Q26 short answer
What are the three strategies to be implemented in India to attain total reproductive health ?

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Q27 short answer
Why are sex linked recessive characters more common in the male human beings ?

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Q28 short answer
What are the three structural differences between RNA and DNA ?

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Q29 short answer
What do you think about it is not possible to produce vaccine against “common cold” ?

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Q30 short answer
What is SMOG and how is it harmful for us ?

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Q31 short answer
What is gene “knock out” ?

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Q32 short answer
Name the active chemical found in the medicinal plant Rauwolfia Vomitoria. What type of diversity it belongs to ?

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Q33 short answer
Classify the antibiotics based on their action on bacteria.

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Q34 long answer 5 marks
(a) Describe the structure of the human ovum with a neat labelled diagram. OR (b) Give an account on population regulation.

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