Question

Match the terms in Column-I with their description in Column-II and choose the correct option:

Column-I		Column -II
(a)	Dominance	(i)	Many genes govern a single character
(b)	Codominance	(ii)	In a heterozygous organism only one allele expresses itself
(c)	Pleiotropy	(iii)	In a heterozygous organism both alleles express themselves fully
(d)	Polygenic inheritance	(iv)	A single gene influences many characters

• A. a - ii; b - iii; c - iv; d - i
• B. a - ii; b - i; c - iv; d - iii
• C. a - iv; b - i; c - ii; d - iii
• D. a - iv; b - iii; c - i; d - ii

Answer 1

The Correct Option is A

(a) Dominance → (ii) 
Dominance refers to a situation where, in a heterozygous organism (having two different alleles), only one allele expresses itself in the phenotype. 
For example, in pea plants, the allele for tallness ($T$) is dominant over the allele for dwarfness ($t$). So, in a plant with genotype $Tt$, only tallness is expressed.

(b) Codominance → (iii)
Codominance occurs when, in a heterozygous organism, both alleles express themselves fully and equally in the phenotype. 
A classic example is the human blood group $AB$, where both alleles $I^A$ and $I^B$ are codominant and are expressed equally.

(c) Pleiotropy → (iv)
Pleiotropy is a genetic phenomenon where a single gene affects multiple traits or characters in an organism. 
For example, the gene responsible for sickle cell anemia affects the shape of red blood cells, resistance to malaria, and causes anemia — multiple traits affected by one gene.

(d) Polygenic Inheritance → (i)
Polygenic inheritance occurs when multiple genes control a single character, usually leading to a continuous range of phenotypes. 
Examples include skin color, height, and eye color in humans, which are influenced by the combined effect of many genes.

Final Matched Answer:
\(\boxed{a - ii;\quad b - iii;\quad c - iv;\quad d - i}\)