Question

Choose the correct answer from the alternatives given.
In a certain plant, yellow fruit colour (Y) is dominant to green fruit colour (y) and round shape (R) is dominant to oval shape (r). The two genes involved are located on different chromosomes.
Which of the following is correct for the condition when plant YyRr is back crossed with the double recessive parent?

• A. 9:3:3:1 Ratio of Phenotypes only
• B. 9 : 3: 3: 1 Ratio of Genotypes only
• C. 1: 1: 1: 1 Ratio of Phenotypes only
• D. 1: 1: 1: 1 Ratio of Phenotypes and Genotypes

Answer 1

The correct option is D 1: 1: 1: 1 Ratio of Phenotypes and Genotypes

When YyRr is crossed with double recessive parent then genotypic and phenotypic ratio is 1:1:1:1. Phenotypic ratio = 1 yellow round : 1 yellow oval : 1 green round : 1 green and oval. This represents a test cross.