Match the following: Column – I (a) Dominance (b) Codominance (c) Pleiotropy (d) Polygenic inheritance Column – II (i) Many genes govern a single character (ii) In a heterozygous organism only one allele expresses itself (iii) In a heterozygous organism both alleles express themselves fully (iv) A single gene influences many characters
Answer: (B) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i). Answer: (B) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i) Solution: In dominance, a heterozygote expresses only one allele (ii).
- A.(a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
- B.(a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)✓
- C.(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
- D.(a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
Correct Answer
(B) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
Solution & Explanation
Answer: (B) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i) Solution: In dominance, a heterozygote expresses only one allele (ii). In co-dominance both alleles express themselves fully, as in IA and IB of ABO blood groups (iii). Pleiotropy is one gene influencing many characters, e.g., phenylketonuria (iv). Polygenic inheritance is many genes governing one character, e.g., human skin colour (i). NCERT Reference: NCERT Class XII, Ch 4, p.69, lines 25-27: "There are however instances where a single gene can exhibit multiple phenotypic expression. Such a gene is called a pleiotropic gene."