Question

In summer squash, white fruit (H) is dominant over yellow (h), and the flattened disc-shaped fruit (D) is dominant over the spherical fruit (d). Examine this cross: HHdd x hhRD, and answer the following questions. (You can use a Punnett square to answer the questions, but you do not need to include it on this worksheet. If you do, it will not be graded.)

a) Does this cross represent a monohybrid cross or a dihybrid cross?
b) What percentage of the offspring from this cross are expected to have the HHDD genotype?
c) What percentage of the offspring from this cross are expected to have the hhDD genotype?
d) What percentage of the offspring from this cross are expected to have the HhDd genotype?
e) What percentage of the offspring from this cross are expected to produce white and disc-shaped fruits?
f) What percentage of the offspring from this cross are expected to produce white and spherical fruits?
g) What percentage of the offspring from this cross are expected to produce yellow and disc-shaped?

Answer 1

a. It is a dihybrid cross

b. 0%

c. 0%

d. 0%

e. 100%

f. 0%

g. 0%

Note: Answers are given assuming that hhRD = hhDD

Step-by-step explanation:

a. The cross, HHdd x hhDD is a dihybrid cross involving two traits: fruit colour and fruit shape

2. Gametes produced in the cross are given below:

for HHdd= Hd and Hd

For hhDD = hD and hD

Offspring produced in the cross:

All HhDd, which represents white and the flattened disc-shaped fruit white since They are both dominant characters.

b. Percentage of the offspring from this cross expected to have the HHDD genotype = 0%

c. Percentage of the offspring from this cros expected to have the hhDD genotype = 0%

d. Percentage of the offspring from this cross expected to have the HhDd genotype = 0%

e. Percentage of the offspring from this cross are expected to produce white and disc-shaped fruits (HHDD or HhDD or HhDd) = 100%

f. Percentage of the offspring from this cross expected to produce white and spherical fruits (HHdd or Hhdd) = 0%

g. Percentage of the offspring from this cross expected to produce yellow and disc-shape (hhDD or hhDd) = 0%