Question

Write down the ratio of the progeny obtained from cross of RrYy and rryy

Answer 1

Genotypic ratio =1:1:1:1
phenotypic ratio = 1:1:1:1

Answer 2

Answer:

The following ratio of offspring is obtained from the given cross:

1. Genotypic ratio : 1 : 1 : 1 : 1.
2. Phenotypic ratio : 1 : 1 : 1 : 1.

Explanation:

• The gametes obtained from the RrYy parent are : RY, Ry, rY and ry.
• The gametes obtained from the rryy parent are only one type : ry.
• The cross between these two parents will give rise to offspring having the following genotypes: RrYy, Rryy, rrYy and rryy.
• Therefore, four genotypes are possible in equal ratio, that is, 1 : 1 : 1 : 1.
• Each of the genotypes will have a different phenotype in equal ratio, that is, 1 : 1 : 1 : 1.
• This is an example of a test-cross, as one of the parents used for the cross is having homozygous recessive genotype (rryy).