Question

A teacher prepared a dihybrid cross Punnett square and a key to dominant and recessive traits.

Answer 1

There are four phenotypes: tall, short, round, wrinkled

Let us say that for the high trait, tall dominates over short. For the shape trait, round dominates over wrinkled. This is:

T allele determines tall plants

t allele determines short plants

R allele determines rounded seeds

r allele determines wrinkled seeds.

The fact that parental are dihybrid, tells us that their genotypes were TtRr

Cross:

Parental) TtRr x TtRr

Gametes) TR tR Tr tr TR tR Tr tr

Punnet Square) TR tR Tr tr

TR TTRR TtRR TTRr TtRr

tR TtRR ttRR TtRr ttRr

Tr TTRr TtRr TTrr Ttrr

tr TtRr ttRr Ttrr ttrr

F1) Genotype and Phenotype

1/16 TTRR Tall, round

2/16 TtRR Tall, round

2/16 TTRr Tall, round

1/16 ttRR Short, round

4/16 TtRr Tall, round

2/16 ttRr Short, round

1/16 TTrr Tall, wrinkled

2/16 Ttrr Tall, wrinkled

1/16 ttrr Short, wrinkled

Phenotypic proportions

9/16 Tall, round

3/16 Tall, wrinkled

3/16 Short, round

1/16 Short, wrinkled

(not my answer.)