Question

Which of the following is correct for the condition when plant YyRr is back crossed with the double recessive parent?

विकल्प

• 9 : 3 : 3 : 1 ratio of phenotypes only

• 9 : 3 : 3 : 1 ratio of genotypes only

• 1 : 1 : 1 : 1 ratio of phenotypes only

• 1 : 1 : 1 : 1 ratio of phenotypes and genotypes

Answer 1

1 : 1 : 1 : 1 ratio of phenotypes and genotypes

Explanation:

Four different types of gametes are produced by the plant with genotype YyRr : YR : Yr : yR : yr. Only one type of gamete with genotype yr is produced by the double recessive plant, which has genotype yyrr. A 1 : 1 : 1 : 1 phenotypic and genotypic ratio results from crossing.

Parents: YyRr × yyrr

	YR	Yr	yR	yr
yr	YyRr	Yyrr	yyRr	yyrr