Question

genetic term color-coding practice name______
for each problem, you will do the following steps:

• underline the dominant trait information in red. (ex. blue flowers are dominant to white)
• underline the recessive trait information in blue.
• circle the parents’ info the following color: green if homozygous, orange if heterozygous. this includes on the punnett square as well as the word problem
• put a red star next to any offspring information
• put a yellow box around any genotype information.
• put a purple box around any phenotype information.

example problem (see genetics powerpoint)
let’s say in humans, six fingers (f) is the dominant trait and five fingers (f) is the recessive trait. both parents are heterozygous and have six fingers.
genotype ratio ff – 25% or 1, ff – 50% or 2, ff- 25% or 1
phenotype ratio – 6 fingers – 75% or 3, 5 finger, 25% or 1
practice problems

1. in peas, yellow color (y) is dominant to green color (y). a heterozygous yellow is crossed with a green. what is the expected phenotype ratio of the offspring?

genotype ratio – yy – 50% or 2, yy- 50% or 2
phenotype ratio – yellow – 50% or 2, green – 50% or 2

1. white color (w) is dominant to yellow color (w) in squash. a heterozygous white fruit plant is crossed with a yellow fruit plant. what is the expected phenotype ratio of the offspring?

genotype ratio – ww – 50% or 2, ww – 50% or 2
phenotype ratio – white fruit – 50% or 2, yellow fruit – 50% or 2

Explanation:

Step1: Identify parent genotypes

Heterozygous white: $Ww$; Yellow: $ww$

Step2: Set up Punnett Square

$$\begin{array}{c|cc} & W & w \\ \hline w & Ww & ww \\ w & Ww & ww \\ \end{array}$$

Step3: Calculate phenotype ratio

White ($Ww$): $\frac{2}{4}=50\%$; Yellow ($ww$): $\frac{2}{4}=50\%$

Step1: Identify parent genotypes

Heterozygous yellow: $Yy$; Green: $yy$

Step2: Set up Punnett Square

$$\begin{array}{c|cc} & Y & y \\ \hline y & Yy & yy \\ y & Yy & yy \\ \end{array}$$

Step3: Calculate phenotype ratio

Yellow ($Yy$): $\frac{2}{4}=50\%$; Green ($yy$): $\frac{2}{4}=50\%$

Answer:

Phenotype Ratio: White fruit – 50% or 2, Yellow fruit – 50% or 2

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For Problem 1 (already partially completed):