Match List-I with List-II
| List-I Terms | List-II Examples |
|---|---|
| (A) Chromosomal disorder | (I) Color Blindness |
| (B) Incomplete dominance | (II) Drosophila |
| (C) Sex-linked recessive disorder | (III) Antirrhinum |
| (D) Male heterogamety | (IV) Down's Syndrome |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
(A) Chromosomal disorder — this matches (IV) Down’s Syndrome. A chromosomal disorder comes from an extra, missing or wrongly placed chromosome. Down’s syndrome is caused by an extra copy of chromosome 21 (trisomy 21).
(B) Incomplete dominance — this matches (III) Antirrhinum. In the dog flower (snapdragon, Antirrhinum), a cross of red (RR) and white (rr) flowers gives pink (Rr) flowers in F1. Neither allele is fully dominant, so the hybrid is in between.
(C) Sex-linked recessive disorder — this matches (I) Color Blindness. The gene for colour blindness is recessive and lies on the X chromosome. So it shows far more often in males, who have only one X.
(D) Male heterogamety — this matches (II) Drosophila. In Drosophila the male is XY and the female XX. The male makes two kinds of gametes, with X or with Y, so it is the heterogametic sex.