Question

make a punnett square to cross the following parents: a heterozygous brown eyed male with a homozygous blue eyed female. brown eyes are dominant to blue eyes. what are the genotypic and phenotypic ratios? (10pts)

Explanation:

Step1: Define Alleles

Let \( B \) represent the dominant brown - eye allele and \( b \) represent the recessive blue - eye allele. The heterozygous brown - eyed male has a genotype of \( Bb \), so he can produce two types of gametes: \( B \) and \( b \) (in equal proportions). The homozygous blue - eyed female has a genotype of \( bb \), so she can only produce \( b \) gametes.

Step2: Construct Punnett Square

	\( B \)	\( b \)
\( b \)	\( Bb \)	\( bb \)

Step3: Determine Genotypic Ratio

Count the number of each genotype. We have 2 \( Bb \) and 2 \( bb \) genotypes. So the genotypic ratio is \( Bb:bb = 2:2=1:1 \).

Step4: Determine Phenotypic Ratio

The genotype \( Bb \) results in the brown - eye phenotype (since \( B \) is dominant), and the genotype \( bb \) results in the blue - eye phenotype. We have 2 brown - eyed (\( Bb \)) and 2 blue - eyed (\( bb \)) offspring. So the phenotypic ratio is brown - eyed: blue - eyed \( = 2:2 = 1:1 \).

Answer:

Genotypic ratio: \( \boldsymbol{1:1} \) ( \( Bb:bb \) ); Phenotypic ratio: \( \boldsymbol{1:1} \) (brown - eyed: blue - eyed)