Question

Student to attempt either option-(A) or (B):
(A) Write the features a molecule should have to act as a genetic material. In the light of the above features, evaluate and justify the suitability of the molecule that is preferred as an ideal genetic material. 
OR 
(B) Differentiate between the following:

• [(i)] Polygenic Inheritance and Pleiotropy
• [(ii)] Dominance, Codominance and Incomplete dominance

Hint:

DNA is preferred as genetic material because of its stability, ability to replicate, and storage of vast genetic information. Understanding dominance types helps decode trait expression patterns.

Answer 1

(A) Characteristics of an Ideal Genetic Material:

• Accurate replication capability.
• Capacity to store all genetic information.
• Ability to express information as observable traits (phenotypes).
• Potential for occasional mutations to facilitate variation and evolution.
• Chemical and structural stability.

Rationale: DNA is regarded as the most suitable genetic material because it satisfies all the above criteria. It replicates through a semi-conservative mechanism, remains chemically stable under physiological conditions, and stores genetic information in the sequence of nitrogenous bases. Additionally, DNA undergoes mutations at a low but significant frequency, enabling genetic variation and evolution while maintaining overall stability.

OR

(B)

(i)

Polygenic Inheritance	Pleiotropy
A single trait is controlled by multiple genes.	A single gene influences multiple traits.
Example: Human skin colour.	Example: Sickle-cell anaemia affects multiple organs.

(ii)

Dominance	Codominance	Incomplete Dominance
One allele masks the expression of the other allele.	Both alleles express equally in the heterozygote.	The heterozygote exhibits an intermediate phenotype.
Example: Tall (T) dominates dwarf (t) in pea plants.	Example: AB blood group.	Example: Pink flowers in snapdragon plants.