A dihybrid heterozygous round, yellow seeded garden pea (Pisum
sativum) was crossed with a double recessive plant.
(i) What type of cross is this?
(ii) Work out the genotype and phenotype of the progeny.
(iii) What principle of Mendel is illustrated through the result of this
cross?

Dear student

Please refer the solution below for the said query


The genotype of heterozygous round and yellow seeded pea plant will be RrYy and double recessive plant with contrasting traits will be rryy.

i. It is a dihybrid test cross


ii. The genotype and phenotype of the progeny can be shown by punnet square as follows:

 

Parents                RrYy                x         rryy Gametes       RY, Ry, rY, ry                       ry Offsprings         ry RY RrYy (Round Yellow)   Ry Rryy (Round Green)   rY rrYy (Wrinkled Yellow)   ry rryy (Wrinkled Green)

 
Phenotype: Round Yellow, Round Green, Wrinkled Yellow and Wrinkled green 
Genotype:        RrYy,               Rryy,                  rrYy,                         rryy   

Phenotypic ratio : 1 : 1 : 1 : 1 Genytopic ratio : 1 : 1 : 1 : 1

iii. It shows the principle of independent assortment.


Hope this information clears your doubt about the topic.

Regards