TAMIL NADU STATE BOARD CLASS 12 BOTANY 2026 Solutions &

Q5 mcq 1 mark

The enzyme which eliminates the torsional stress caused by the unwinding of double helix during the DNA replication is :

a.

Topoisomerase Correct Answer

b.

DNA Polymerase

c.

RNA Primase

d.

Ligase

Step-by-Step AI Explanation

Verified Method

Topoisomerase is the enzyme that removes the torsional stress and supercoiling generated ahead of the replication fork during DNA unwinding. DNA polymerase synthesizes the new DNA strand, RNA primase synthesizes the RNA primer, and ligase joins Okazaki fragments.

Q7 mcq 1 mark

Genetic engineering is :

a.

Production of alcohol by using micro-organisms.

b.

Making artificial genes.

c.

Making artificial limbs, diagnostic instruments such as ECG, EEG etc.,

d.

Hybridization of DNA of one organism to that of the others. Correct Answer

Step-by-Step AI Explanation

Verified Method

Genetic engineering refers to the deliberate manipulation and transfer of DNA from one organism to another, or the construction of recombinant DNA. Hence, hybridization of DNA of one organism with that of another is the correct choice. The other options describe fermentation, gene synthesis in a limited sense, and bioengineering devices, not genetic engineering.

Q8 mcq 1 mark

Pedogenesis refers to :

a.

Population

b.

Fossils

c.

Soil Correct Answer

d.

Water

Step-by-Step AI Explanation

Verified Method

Pedogenesis means soil formation. So the correct answer is Soil.

Q9 mcq 1 mark

Match List - I with List - II : List - I List - II (1)Sterilization of culture room (i)Macerozyme (2)Fusion of protoplast (ii)Ethanol (3)Solidifying agent (iii)Agar (4)Isolation of protoplast (iv)Polyethylene Glycol

a.

(1) - (ii), (2) - (iv), (3) - (iii), (4) - (i) Correct Answer

b.

(1) - (i), (2) - (iv), (3) - (iii), (4) - (ii)

c.

(1) - (iv), (2) - (iii), (3) - (ii), (4) - (i)

d.

(1) - (i), (2) - (ii), (3) - (iii), (4) - (iv)

Step-by-Step AI Explanation

Verified Method

The correct matching is: (1) Sterilization of culture room → Ethanol, (2) Fusion of protoplast → Polyethylene Glycol, (3) Solidifying agent → Agar, (4) Isolation of protoplast → Macerozyme. Therefore, option A is correct.

Q9 mcq

Match List - I with List - II:

a.

(1) - (ii), (2) - (iv), (3) - (iii), (4) - (i) Correct Answer

b.

(1) - (i), (2) - (iv), (3) - (iii), (4) - (ii)

c.

(1) - (iv), (2) - (iii), (3) - (ii), (4) - (i)

d.

(1) - (i), (2) - (ii), (3) - (iii), (4) - (iv)

Step-by-Step AI Explanation

Verified Method

The correct match is option A: (1) - (ii), (2) - (iv), (3) - (iii), (4) - (i).

Q10 mcq 1 mark

Pond is a type of :

a.

Marine ecosystem

b.

Forest ecosystem

c.

Freshwater ecosystem Correct Answer

d.

Grassland ecosystem

Step-by-Step AI Explanation

Verified Method

A pond is a freshwater ecosystem because it contains non-saline water and supports freshwater organisms. It is neither marine nor a forest or grassland ecosystem.

Q11 mcq 1 mark

In which technique is Ethidium Bromide used ?

a.

Polymerase Chain Reaction

b.

Southern Blotting Technique

c.

Agarose Gel Electrophoresis Correct Answer

d.

Western Blotting Technique

Step-by-Step AI Explanation

Verified Method

Ethidium bromide is used in agarose gel electrophoresis to stain DNA bands and view them under UV light. It is not used in PCR or blotting techniques as the main staining agent.

Q12 mcq

Which one is in descending order of a food chain ?

a.

Tertiary consumers → Secondary consumers → Primary consumers → Producers Correct Answer

b.

Producers → Secondary consumers → Primary consumers → Tertiary consumers

c.

Tertiary consumers → Producers → Primary consumers → Secondary consumers

d.

Tertiary consumers → Primary consumers → Secondary consumers → Producers

Step-by-Step AI Explanation

Verified Method

In a food chain, energy flows from lower trophic levels to higher ones. The descending order from top consumers to producers is: Tertiary consumers → Secondary consumers → Primary consumers → Producers. Hence option A is correct.

Q13 mcq

Plant indicator for $SO_2$ pollution is :

a.

Gladiolus, Eucalyptus

b.

Petunia, Chrysanthemum

c.

Robinia pseudoacacia, Casuarina

d.

Lichens, Rose Correct Answer

Step-by-Step AI Explanation

Verified Method

Lichens are highly sensitive to sulfur dioxide ($SO_2$) pollution, so they are used as plant indicators of air pollution. Roses are also sensitive to polluted air. The other pairs are not standard indicators for $SO_2$ pollution.

Q14 mcq

Plants having similar genotypes produced by plant breeding are called :

a.

Autopolyploid

b.

Clone Correct Answer

c.

Genome

d.

Haploid

Step-by-Step AI Explanation

Verified Method

Plants having similar genotypes produced by plant breeding are called a clone. A clone is a group of genetically identical individuals produced from a single parent. Autopolyploid refers to multiplication of the same genome, genome is the complete genetic material, and haploid means having a single set of chromosomes.

Q15 mcq

Which one of the following matches is correct ?

a.

Steveocide - Natural Sweetener

b.

Palmyra - Native of Brazil

c.

Palmyra sap - Fermented to give ethanol

d.

Saccharum - Abundant in Kanyakumari

Correct Answer & Step-by-Step Solution Locked