Question

In a cross between two heterozygous individuals (eg. Rr X Rr), the expected phenotypic ratio of the offspring would be A) 1:2:2:1. B) 1:2:1. C) 1:1. D) 3:1.

Answer 1

3:1. The physical appearance of the offspring will be 3 organisms that look like the parents: 1 individual that differs in appearance.

Answer 2

In a cross between two heterozygous individuals (eg. Rr X Rr), the expected phenotypic ratio of the offspring would be 3:1.

Reason:

When we cross Rr X Rr

we get

RR Rr Rr rr

Since R is dominant over r, the individuals with genotype RR and Rr will have the dominant phenotype. This implies that 3 offsprings will have dominant phenotype and 1 offspring (rr) will have recessive phenotype.

Thus the phenotypic ratio will be 3:1.

The image for the Punnett cross displaying this cross is attached for a better understanding of how the cross is made.