Question

the following for questions 7-9:
ogs, there is hereditary deafness caused by a recessive gene, \d.\ a kennel owner has a male
dog (gilbert) that she wants to use for breeding purposes if possible. gilbert has the ability to hear.

1. what are the two possible genotypes of gilbert?
2. create two punnett squares to illustrate the crosses for your possible male genotypes (from

question 7) with a deaf female dog (dd)
possible cross 1
% of possible genotypes:
dd: 0%
dd: 50%
dd: 50%
% of possible phenotypes:
deaf pups: 50%
hearing pups: 50%
possible cross 2
% of possible genotypes:
dd: ______
dd: ______
dd: ______
% of possible phenotypes:
deaf pups: ______
hearing pups: ______

Explanation:

Step1: Determine Gilbert's Genotypes (from Q7)

Gilbert can hear, so his genotype is either \( DD \) (homozygous dominant) or \( Dd \) (heterozygous) (since deafness is recessive, \( dd \) would be deaf).

Step2: Analyze Cross 2 (Gilbert = \( DD \) × Deaf Female \( dd \))

• Genotype of Parents: Male (\( DD \)) and Female (\( dd \)).
• Gametes: Male produces \( D \) only; Female produces \( d \) only.
• Punnett Square Setup:

	\( d \)	\( d \)
\( D \)	\( Dd \)	\( Dd \)

Step3: Calculate Genotype Percentages

• \( DD \): 0% (no \( DD \) combinations).
• \( Dd \): \( \frac{4}{4} = 100\% \) (all offspring are \( Dd \)).
• \( dd \): 0% (no \( dd \) combinations).

Step4: Calculate Phenotype Percentages

• Deaf pups (\( dd \)): 0% (no \( dd \) genotypes).
• Hearing pups (\( Dd \) or \( DD \)): 100% (all \( Dd \) have hearing phenotype).

Answer:

Possible Cross 2 - % of possible Genotypes:

• \( DD \): \( 0\% \)
• \( Dd \): \( 100\% \)
• \( dd \): \( 0\% \)

Possible Cross 2 - % of possible Phenotypes:

• Deaf pups: \( 0\% \)
• Hearing pups: \( 100\% \)