Question

A researcher wanted to cross pollinate two heterozygous yellow round seed producing pea plants. But mistakenly he crossed it with the double recessive (green and wrinkled seed) plant. Which among the following ratio would occur in the progeny?

• A. 9 : 3 : 3 : 1 ratio of phenotypes only
• B. 1 : 1 : 1 : 1 ratio of phenotypes only
• C. 9 : 3 : 3 : 1 ratio of genotypes 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

The given cross represents a dihybrid test cross, When YyRr is crossed with double recessive (yyrr) then the phenotypic and genotypic ratio is 1 : 1 : 1 : 1.
YrRr x yyrr
gametes: for YyRr - YR, Yr, yR, yr
for yyrr - yr

	yr
YR	YyRr (yellow round)
Yr	Yyrr (yellow wrinkled)
yR	yyRr (Green round)
yr	yyrr (Green wrinkled)