Question

1. in humans, straight toes are dominant over curled toes. what would be the result of a cross between a recessive male and a homozygous dominant female?

genotypic ratio ____:__:____
phenotypic ratio ____:____
chances of straight toes? __________

1. curly hair is recessive in humans and straight is dominant. predict the odds of children with straight hair from two homozygous dominant parents.

genotypic ratio ____:__:____
phenotypic ratio ____:____
chances of curly hair? __________

1. in sunflowers, tall is dominant and short is recessive. what are the chances of having short offspring when a homozygous short and a heterozygous tall plant are crossed?

genotypic ratio ____:__:____
phenotypic ratio ____:____
chances of having tall sunflowers? __________

1. in catfish long whiskers are dominant and short are recessive. cross a short whisker fish with a heterozygous fish

genotypic ratio ____:__:____
phenotypic ratio ____:____
chances of offspring having short whiskers? __________

1. in humans producing little ear wax is dominant,large amounts are recessive. cross a male with very waxy ears with a heterozygous female.

genotypic ratio ____:__:____
phenotypic ratio ____:____

Explanation:

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Problem 6

Step1: Assign allele symbols

Let $S$ = straight toes (dominant), $s$ = curled toes (recessive)

Step2: Define parent genotypes

Male: $ss$ (recessive), Female: $SS$ (homozygous dominant)

Step3: Set up Punnett square

	$S$	$S$
$s$	$Ss$	$Ss$

Step4: Calculate ratios/probability

Genotypic ratio: $SS:Ss:ss = 0:4:0$
Phenotypic ratio: Straight:Curled = $4:0$
Chances of straight toes: $\frac{4}{4} = 100\%$

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Problem 7

Step1: Assign allele symbols

Let $H$ = straight hair (dominant), $h$ = curly hair (recessive)

Step2: Define parent genotypes

Both parents: $HH$ (homozygous dominant)

Step3: Set up Punnett square

	$H$	$H$
$H$	$HH$	$HH$

Step4: Calculate ratios/probability

Genotypic ratio: $HH:Hh:hh = 4:0:0$
Phenotypic ratio: Straight:Curled = $4:0$
Chances of curly hair: $\frac{0}{4} = 0\%$

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Problem 8

Step1: Assign allele symbols

Let $T$ = tall (dominant), $t$ = short (recessive)

Step2: Define parent genotypes

Homozygous short: $tt$, Heterozygous tall: $Tt$

Step3: Set up Punnett square

	$T$	$t$
$t$	$Tt$	$tt$

Step4: Calculate ratios/probability

Genotypic ratio: $TT:Tt:tt = 0:2:2$ (simplified $0:1:1$)
Phenotypic ratio: Tall:Short = $2:2$ (simplified $1:1$)
Chances of tall sunflowers: $\frac{2}{4} = 50\%$

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Problem 9

Step1: Assign allele symbols

Let $W$ = long whiskers (dominant), $w$ = short whiskers (recessive)

Step2: Define parent genotypes

Short whisker: $ww$, Heterozygous: $Ww$

Step3: Set up Punnett square

	$W$	$w$
$w$	$Ww$	$ww$

Step4: Calculate ratios/probability

Genotypic ratio: $WW:Ww:ww = 0:2:2$ (simplified $0:1:1$)
Phenotypic ratio: Long:Short = $2:2$ (simplified $1:1$)
Chances of short whiskers: $\frac{2}{4} = 50\%$

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Problem 10

Step1: Assign allele symbols

Let $E$ = little ear wax (dominant), $e$ = large ear wax (recessive)

Step2: Define parent genotypes

Male (very waxy): $ee$, Female (heterozygous): $Ee$

Step3: Set up Punnett square

	$E$	$e$
$e$	$Ee$	$ee$

Step4: Calculate ratios/probability

Genotypic ratio: $EE:Ee:ee = 0:2:2$ (simplified $0:1:1$)
Phenotypic ratio: Little wax:Much wax = $2:2$ (simplified $1:1$)
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Answer:

1. Problem 6

Genotypic ratio: $\boldsymbol{0:4:0}$
Phenotypic ratio: $\boldsymbol{4:0}$
Chances of straight toes: $\boldsymbol{100\%}$

1. Problem 7

Genotypic ratio: $\boldsymbol{4:0:0}$
Phenotypic ratio: $\boldsymbol{4:0}$
Chances of curly hair: $\boldsymbol{0\%}$

1. Problem 8

Genotypic ratio: $\boldsymbol{0:1:1}$
Phenotypic ratio: $\boldsymbol{1:1}$
Chances of tall sunflowers: $\boldsymbol{50\%}$

1. Problem 9

Genotypic ratio: $\boldsymbol{0:1:1}$
Phenotypic ratio: $\boldsymbol{1:1}$
Chances of short whiskers: $\boldsymbol{50\%}$

1. Problem 10

Genotypic ratio: $\boldsymbol{0:1:1}$
Phenotypic ratio: $\boldsymbol{1:1}$