question_answer

                In Mendel's experiments with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), yellow cotyledon CYY) was dominant over green cotyledon (yy).               What are the expected phenotypes in the \[{{F}_{2}}\] generation of the cross \[RRYY\times rryy\]?                                                                                                   

A)                  Only round seeds with green cotyledons

B)                  Only wrinkled seeds with yellow cotyledons

C)                  Only wrinkled seeds with green cotyledons

D)                  Round seeds with yellow cotyledons and wrinkled seeds with yellow cotyledons            

Correct Answer: D

Solution :

                When a cross (dihybrid) is made between plants bearing round yellow (RRYY) and wrinkled green (rryy) seeds, all die plants in \[{{F}_{1}}\]                 \[{{F}_{1}}\] generation are with yellow round seeds (showing the genotype RrYy). The phenotype in \[{{F}_{2}}\] will be as follows: