Question

Parent Plant one’s gametes are as follows:

Gamete 1: PR
Gamete 2: Pr
Gamete 3: pR
gamete 4: pr

Parent Plant Two:
Gamete 1: PR
Gamete 2: Pr
Gamete 3: pR
Gamete 4: pr

Create a Punnett square to calculate the possible genotypes that can result from a cross between the two parent plants. In a dihybrid cross, the alleles of the gametes of each parent are written along the left side and top of the Punnett square, just as they are for a monohybrid cross. Fill in the squares with the predicted genotypes.

Answer 1

In a dihybrid cross, the alleles of the gametes of each plant parent (PpRr x PpRr) are written along the left side and top to the Punnett square drawing. We can calculate the outcome of the genetic cross of (PpRr x PpRr). Since each parent has four different combinations of alleles in the gametes, there are sixteen possible. There will be nine (9) individuals with both dominant traits, three (3) individuals dominant for one trait, three (3) individuals dominant for the other trait and only one individual recessive for both traits.

In this case, we are looking at a subcategory of the plants dominant for both traits. Four of these nine will be heterozygous for both traits. The ratios can be represented as: 9:3:3:1.

For further information, please see the image attached.