Tamil Nadu Board 2026 Class 12 Zoology Public Question Paper with Solutions - Available

This pedigree symbol represents:

• (A) Male
• (B) Monozygotic twins
• (C) Mating
• (D) Dizygotic twins

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

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.

_________ is/are an ideal disinfectant for waste water.

• (A) Boiling
• (B) U-V Rays
• (C) Ozonisation
• (D) Chlorination

Assertion (A): In nature many organisms produce clones through asexual reproduction.

Reason (R): By this process, genetically identical individuals are produced.

• (A) Both Assertion and Reason are false.
• (B) Assertion is true, but Reason is false.
• (C) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
• (D) Both Assertion and Reason are true and Reason explains Assertion correctly.

The relationship between sucker fish and shark is __________.

• (A) Predation
• (B) Competition
• (C) Parasitism
• (D) Commensalism

Allergy involves:

• (A) IgA
• (B) IgE
• (C) IgM
• (D) IgG

The wings of birds and butterflies is an example of:

• (A) Divergent evolution
• (B) Adaptive radiation
• (C) Variation
• (D) Convergent evolution

The most common substrate used in distilleries for the production of ethanol is __________.

• (A) Molasses
• (B) Soya meal
• (C) Corn meal
• (D) Groundgram

The term “Niche” was first used by _________.

• (A) John Ray
• (B) Charles Darwin
• (C) Jordon
• (D) Charles Elton

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.

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.

In which type of Parthenogenesis are only males produced?

• (A) Arrhenotoky
• (B) Thelytoky
• (C) Amphitoky
• (D) Both (a) and (c)

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

Which one of the following are at higher risk of extinction due to habitat destruction?

• (A) Amphibians
• (B) Mammals
• (C) Echinoderms
• (D) Birds