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.

1. Describe how you would set up a Punnett square for this cross.

2. List the likelihood of each possible offspring genotype.

3. List the likelihood of each possible offspring phenotype.

Answer 1

Answer No 1:

The set up of the punnet square is shown in the attached diagram. As the alleles assort independently hence the gametes formed will be OT,Ot,OT,Ot and OT,Ot,oT,ot. These will be the outcomes of the possible gametes formed. When these gametes are cross bred, the results are shown in the diagram attached.

Answer No 2:

The outcomes of each possible genotype are:

OOTT = 2/16

OOTt = 4/16

OOtt = 2/16

Oott = 2/16

OoTT = 2/16

OoTt = 4/16

Answer No 3:

The likelihood of each possible offspring phenotype is:

Orange petals with tall stem and orange petals with small stems present in ratio 12:4 i.e. 3:1.