Question

A dihybrid tall and yellow pea plant crossed with double recessive plant.
What type of cross?
Phenotypic and genotypic ratio ?

Answer 1

Explanation:

RY Ry rY ry

ry RrYy (round yellow) Rryy (round green) rrYy (wrinkled yellow) rryy (wrinkled green)

Heterozygous pea: RrYy

Double recessive parent: rryy

(a) This is dihybrid cross as there are two characters being studied simultaneously.

(b) Genotype: All four combinations appear once i.e. RrYy, Rryy, rrYy, and rryy. (1: 1: 1: 1)

Phenotypes: Round yellow, round green, wrinkled yellow, wrinkled green. (1: 1: 1: 1).

(c) This cross illustrates the law of independent assortment which states that the inheritance pattern of one kind of character is independent of the inheritance pattern of the other character. Here, inheritance of seed shape (round or wrinkled) is independent of the inheritance of seed colour (yellow or green).