Question

1. in humans, widow peaks are dominant to straight hairlines and freckles are dominant to no freckles. a woman who is homozygous for her widow’s peak and heterozygous for freckles marries a man that has a straight hairline and is also heterozygous for freckles. determine the phenotypic ratio. what is the probability that they have a child who looks like dad? 20. in humans, almond - shaped eyes are dominant to round - shaped eyes and long eyelashes are dominant to short. a man who has round eyes and homozygous long eyelashes marries a woman who is heterozygous for both traits. determine the phenotypic ratio. if they have 8 children, how many will have almond - shaped eyes with long eyelashes?

Explanation:

Step1: Define alleles

Let \(W\) represent the allele for widow - peak (dominant) and \(w\) for straight hairline (recessive). Let \(F\) represent the allele for freckles (dominant) and \(f\) for no freckles (recessive). The woman's genotype is \(WWFf\) and the man's genotype is \(wwFf\).

Step2: Determine gametes

The woman can produce gametes \(WF\) and \(Wf\) in a 1:1 ratio. The man can produce gametes \(wF\) and \(wf\) in a 1:1 ratio.

Step3: Create a Punnett - square

	WF	Wf
wf	WwFf	Wwff

Step4: Calculate phenotypic ratio

The phenotypes are widow - peak with freckles (\(WwFF\) and \(WwFf\)) and widow - peak without freckles (\(Wwff\)). The phenotypic ratio of widow - peak with freckles : widow - peak without freckles is 3:1.

Step5: Calculate probability of child looking like dad

The dad has a straight hairline and freckles (\(wwF -\)). Since the woman is \(WW\), the probability of having a child with a straight hairline (\(ww\)) is 0. So the probability of having a child who looks like dad is 0.

Answer:

Phenotypic ratio: 3 widow - peak with freckles : 1 widow - peak without freckles; Probability of child looking like dad: 0