Question

1. if the dogs genotype is dd, the owner does not wish to use him for breeding so that the deafness gene will not be passed on. this can be tested by breeding the dog to a deaf female (dd). fill in these two punnett squares to illustrate the crosses for your possible male genotypes (from question 9) with the deaf female dog.

possible cross 1
% of possible genotypes:
dd: ______
dd: ______
dd: ______
% of possible phenotypes:
deaf pups: ______
hearing pups: ______
possible cross 2
% of possible genotypes:
ff: ______
ff: ______
ff: ______
% of possible phenotypes:
deaf pups: ______
hearing pups: ______

1. explain how could you tell the genotype of gilbert’s male dog?

Explanation:

Possible Cross 1 (Assuming male genotype is Dd, crossing with dd)

Step1: Determine gametes

Male (Dd) produces D and d gametes. Female (dd) produces d and d gametes.

Step2: Fill Punnett square

	d	d
d	dd	dd

Step3: Calculate genotype percentages

• DD: 0% (no DD in square)
• Dd: $\frac{2}{4} \times 100 = 50\%$
• dd: $\frac{2}{4} \times 100 = 50\%$

Step4: Calculate phenotype percentages

• Deaf (dd): 50%
• Hearing (Dd, DD): 50% (since D is dominant, Dd is hearing)

Possible Cross 2 (Assuming a typo, maybe male genotype is DD, crossing with dd)

Step1: Determine gametes

Male (DD) produces D and D gametes. Female (dd) produces d and d gametes.

Step2: Fill Punnett square

	d	d
D	Dd	Dd

Step3: Calculate genotype percentages (note: FF, Ff, ff are likely a typo, should be DD, Dd, dd)

• DD: 0% (no DD in square)
• Dd: 100% (all squares are Dd)
• dd: 0%

Step4: Calculate phenotype percentages

• Deaf (dd): 0%
• Hearing (Dd): 100%

Question 9 Explanation:

To determine the genotype of the male dog (either DD or Dd, assuming hearing phenotype since deaf is dd), we perform a test cross with a deaf female (dd). If the male is DD, all offspring will be Dd (hearing, 0% deaf pups). If the male is Dd, the offspring will be 50% Dd (hearing) and 50% dd (deaf). By observing the phenotype of the offspring from the test cross, we can infer the genotype: if any deaf pups (dd) are produced, the male is Dd; if all pups are hearing, the male is DD.

Answer:

s:

Possible Cross 1

• % of possible Genotypes:
• DD: 0%
• Dd: 50%
• dd: 50%
• % of possible Phenotypes:
• Deaf pups: 50%
• Hearing pups: 50%

Possible Cross 2 (correcting genotype labels to DD, Dd, dd)

• % of possible Genotypes:
• DD: 0%
• Dd: 100%
• dd: 0%
• % of possible Phenotypes:
• Deaf pups: 0%
• Hearing pups: 100%

Question 9

To tell the genotype, perform a test cross with a deaf female (dd). If offspring include deaf pups (dd), the male is Dd. If all offspring are hearing, the male is DD.