Question

c. in humans, oval - shaped eyes (a) are dominant to round - shaped eyes (a). cross a female who is homozygous dominant with a male who is homozygous recessive. then, answer the questions that follow.

1. how many possible genotypes are there among the offspring?
2. how many possible phenotypes are there among the offspring?
3. what percentage of the offspring have oval - shaped eyes?
4. what percentage of the offspring have round - shaped eyes?
5. what eye shape does the female parent have?
6. what eye shape does the male parent have?
7. what is the phenotypic ratio of their offspring?
8. what is the genotypic ratio of their offspring?

aa × aa
d. in tomatoes, red fruit (r) is dominant to yellow fruit (r). cross a homozygous recessive fruit with a heterozygous fruit. answer the questions that follow.

1. how many possible genotypes are there among the offspring?
2. how many possible phenotypes are there among the offspring?
3. what percentage of the offspring are red?
4. what percentage of the offspring are yellow?
5. what is the phenotypic ratio of the offspring?
6. what is the genotypic ratio of the offspring?

rr × rr

Explanation:

Step1: Fill Punnett Square for AA × aa

Female (AA) contributes gametes: $A, A$; Male (aa) contributes gametes: $a, a$

$$\begin{array}{c|cc} & A & A \\ \hline a & Aa & Aa \\ a & Aa & Aa \\ \end{array}$$

Step2: Answer Set C questions

1. Count unique genotypes: only $Aa$ → 1
2. Count unique phenotypes: only oval (A dominant) → 1
3. All offspring have Aa → 100% oval
4. No aa offspring → 0% round
5. Female is AA (dominant) → oval eyes
6. Male is aa (recessive) → round eyes
7. All offspring are oval → 1:0 (oval:round)
8. All offspring are Aa → 1:0 (Aa:aa)

Step3: Fill Punnett Square for rr × Rr

Homozygous recessive (rr) contributes gametes: $r, r$; Heterozygous (Rr) contributes gametes: $R, r$

$$\begin{array}{c|cc} & r & r \\ \hline R & Rr & Rr \\ r & rr & rr \\ \end{array}$$

Step4: Answer Set D questions

1. Count unique genotypes: $Rr, rr$ → 2
2. Count unique phenotypes: red (Rr), yellow (rr) → 2
3. 2 out of 4 offspring are Rr → $\frac{2}{4} \times 100\% = 50\%$ red
4. 2 out of 4 offspring are rr → $\frac{2}{4} \times 100\% = 50\%$ yellow
5. 2 red : 2 yellow → 1:1 (red:yellow)
6. 2 Rr : 2 rr → 1:1 (Rr:rr)

Answer:

Set C (AA × aa)

1. 1
2. 1
3. 100%
4. 0%
5. Oval-shaped eyes
6. Round-shaped eyes
7. 1:0 (oval:round)
8. 1:0 (Aa:aa)

Set D (rr × Rr)

1. 2
2. 2
3. 50%
4. 50%
5. 1:1 (red:yellow)
6. 1:1 (Rr:rr)