Question

punnett square practice worksheet
use the following information for questions 1-3:
in dogs, the gene for fur color has two alleles.
the dominant allele (f) codes for grey fur and the recessive allele (f) codes for black fur.

1. the female dog is heterozygous. the male dog is homozygous recessive.

use a punnett square to predict the most likely phenotypic ratio and genotypic ratio of their possible puppies.

1. the female dog has black fur. the male dog has black fur.

use a punnett square to predict the most likely phenotypic ratio and genotypic ratio of their possible puppies.

1. the female dog is heterozygous. the male dog is heterozygous.

use a punnett square to predict the most likely phenotypic ratio and genotypic ratio of their possible puppies.

Explanation:

Question 1

Step1: Determine Genotypes

Female (heterozygous): \( Ff \)
Male (homozygous recessive): \( ff \)

Step2: Set Up Punnett Square

	\( F \)	\( f \)
\( f \)	\( Ff \)	\( ff \)

Step3: Calculate Ratios

• Genotypic Ratio: \( Ff : ff = 2 : 2 = 1 : 1 \)
• Phenotypic Ratio: Grey (\( Ff \)) : Black (\( ff \)) = \( 2 : 2 = 1 : 1 \)

Step1: Determine Genotypes

Black fur is recessive, so both female and male have genotype \( ff \).

Step2: Set Up Punnett Square

	\( f \)	\( f \)
\( f \)	\( ff \)	\( ff \)

Step3: Calculate Ratios

• Genotypic Ratio: All \( ff \), so \( ff : ff = 4 : 0 = 1 : 0 \) (or just all \( ff \))
• Phenotypic Ratio: All black fur, so Black : Black = \( 4 : 0 = 1 : 0 \) (or all black)

Step1: Determine Genotypes

Both female and male are heterozygous: \( Ff \)

Step2: Set Up Punnett Square

	\( F \)	\( f \)
\( f \)	\( Ff \)	\( ff \)

Step3: Calculate Ratios

• Genotypic Ratio: \( FF : Ff : ff = 1 : 2 : 1 \)
• Phenotypic Ratio: Grey (\( FF, Ff \)) : Black (\( ff \)) = \( 3 : 1 \)

Answer:

Genotypic Ratio: \( 1:1 \) ( \( Ff : ff \) ), Phenotypic Ratio: \( 1:1 \) (Grey : Black)

Question 2