Assuming complete dominance, a phenotypic ratio of is expected from a monohybrid sib or self-cross. a) 1: 1 b) 2: 1 c) 3: 1 d) 5: 2 e) 3: 2

C (3:1)

Explanation:

Gregor Mendel was able to portray complete dominance of an allele over another when he crossed two purebreeding plants; one homozygous for red flowers and the other for white flowers. He discovered that all the F1 offsprings were red-flowered. Hence, he came up with his law of dominance.

He self-crossed the F1 offsprings which were all hybrids or heterozygous i.e. contained a combined allele in their genotype. He discovered that the offsprings produced a phenotypic ratio of 3:1 i.e 3 red-flowered plants to 1 white-flowered plant

The red-flowered plants have genotypes RR, Rr and Rr respectively while the white-flowered plant have a rr genotype.