Question

In one type of plant, orange petals (O) are dominant over yellow petals (o) and tall stems (T) are dominant over short stems (t). Complete a dihybrid cross for parents with the genotypes: OOTt × OoTt and answer the following in complete sentences.

Describe how you would set up a Punnett square for this cross.
List the likelihood of each possible offspring genotype.
List the likelihood of each possible offspring phenotype.

Answer 1

Possible gametes of OOTt are OT and Ot.

Possible gametes of OoTt are OT, Ot, oT, and ot.

The punnet square is shown in the attached figure.

As per the punnet square there are six genotypes and two phenotyes.

The genotypes with ratios are:

OOTT = 2/16

OOTt = 4/16

OOtt = 2/16

Oott = 2/16

OoTT = 2/16

OoTt = 4/16

The two phenotypes "orange with tall stems" and "orange with small stems" will be present in 12:4 i.e. 3:1.