A heterozygous pea plant with violet flowers was crossed with a homozygous pea plant with white flowers. Violet is dominant over white. Which one of the following represents the expected combinations among 40 progenies formed?
Answer: (D) 20 produced violet and 20 produced white flowers. Answer: (D) 20 produced violet and 20 produced white flowers Solution: A heterozygous violet plant (Vv) crossed with a homozygous white plant (vv) is a test cross.
- A.All 40 produced violet flowers
- B.All 40 produced white flowers
- C.30 produced violet and 10 produced white flowers
- D.20 produced violet and 20 produced white flowers✓
Correct Answer
(D) 20 produced violet and 20 produced white flowers
Solution & Explanation
Answer: (D) 20 produced violet and 20 produced white flowers Solution: A heterozygous violet plant (Vv) crossed with a homozygous white plant (vv) is a test cross. The cross Vv x vv yields 1 Vv (violet) : 1 vv (white), i.e., a 1:1 ratio. Out of 40 progeny this gives 20 violet and 20 white, which is option (4). NCERT Reference: NCERT Class XII, Ch 4, p.58, lines 33-37: "In a typical test cross an organism (pea plants here) showing a dominant phenotype (and whose genotype is to be determined) is crossed with the recessive parent instead of self-crossing."