Punnett Square Worksheets - 10 Free PDF Printables | Printablee - Free Printable

Problem: Punnett Square Practice

We are tasked with solving three genetic scenarios using Punnett squares to determine the potential genotypes and phenotypes of offspring. Let's solve each scenario step by step.

---

Scenario 1: Brown-Eyed Homozygous Dominant Female (BB) × Brown-Eyed Heterozygous Male (Bb)

#### Step 1: Identify the Genotypes
- Female: BB (homozygous dominant for brown eyes)
- Male: Bb (heterozygous for brown eyes)

#### Step 2: Create the Punnett Square
The female contributes one allele from her genotype (B), and the male contributes one allele from his genotype (B or b). The Punnett square is set up as follows:

```
| B | B
-------------------
B | BB | BB
-------------------
b | Bb | Bb
```

#### Step 3: Determine Genotypes and Phenotypes
- Genotypes: BB, BB, Bb, Bb
- Phenotypes: All offspring will have brown eyes because "B" (brown) is dominant over "b" (blue).

#### Step 4: List Possibilities
| Possibility | Genotype | Phenotype |
|-------------|----------|-----------|
| 1 | BB | Brown Eyes |
| 2 | BB | Brown Eyes |
| 3 | Bb | Brown Eyes |
| 4 | Bb | Brown Eyes |

---

Scenario 2: Freckles (F) Dominant Over No Freckles (f); Heterozygous Mother (Ff) × Heterozygous Father (Ff)

#### Step 1: Identify the Genotypes
- Mother: Ff (heterozygous for freckles)
- Father: Ff (heterozygous for freckles)

#### Step 2: Create the Punnett Square
The mother contributes one allele from her genotype (F or f), and the father contributes one allele from his genotype (F or f). The Punnett square is set up as follows:

```
| F | f
-------------------
F | FF | Ff
-------------------
f | Ff | ff
```

#### Step 3: Determine Genotypes and Phenotypes
- Genotypes: FF, Ff, Ff, ff
- Phenotypes:
- FF: Freckles (dominant)
- Ff: Freckles (dominant)
- ff: No freckles (recessive)

#### Step 4: List Possibilities
| Possibility | Genotype | Phenotype |
|-------------|----------|-----------|
| 1 | FF | Freckles |
| 2 | Ff | Freckles |
| 3 | Ff | Freckles |
| 4 | ff | No Freckles |

---

Scenario 3: Tongue Rolling (R) Dominant Over Non-Rolling (r); Non-Rolling Woman (rr) × Homozygous Dominant Man (RR)

#### Step 1: Identify the Genotypes
- Woman: rr (homozygous recessive for non-rolling tongue)
- Man: RR (homozygous dominant for rolling tongue)

#### Step 2: Create the Punnett Square
The woman contributes one allele from her genotype (r), and the man contributes one allele from his genotype (R). The Punnett square is set up as follows:

```
| R | R
-------------------
r | Rr | Rr
-------------------
r | Rr | Rr
```

#### Step 3: Determine Genotypes and Phenotypes
- Genotypes: Rr, Rr, Rr, Rr
- Phenotypes: All offspring will be able to roll their tongues because "R" (rolling) is dominant over "r" (non-rolling).

#### Step 4: List Possibilities
| Possibility | Genotype | Phenotype |
|-------------|----------|-----------|
| 1 | Rr | Can Roll Tongue |
| 2 | Rr | Can Roll Tongue |
| 3 | Rr | Can Roll Tongue |
| 4 | Rr | Can Roll Tongue |

---

Final Answers

1. Brown-Eyed Homozygous Dominant Female (BB) × Brown-Eyed Heterozygous Male (Bb)
```
| Possibility | Genotype | Phenotype |
|-------------|----------|----------------|
| 1 | BB | Brown Eyes |
| 2 | BB | Brown Eyes |
| 3 | Bb | Brown Eyes |
| 4 | Bb | Brown Eyes |
```

2. Heterozygous Mother (Ff) × Heterozygous Father (Ff)
```
| Possibility | Genotype | Phenotype |
|-------------|----------|----------------|
| 1 | FF | Freckles |
| 2 | Ff | Freckles |
| 3 | Ff | Freckles |
| 4 | ff | No Freckles |
```

3. Non-Rolling Woman (rr) × Homozygous Dominant Man (RR)
```
| Possibility | Genotype | Phenotype |
|-------------|----------|--------------------|
| 1 | Rr | Can Roll Tongue |
| 2 | Rr | Can Roll Tongue |
| 3 | Rr | Can Roll Tongue |
| 4 | Rr | Can Roll Tongue |
```

Boxed Final Answer

\[
\boxed{
\begin{array}{l}
\text{1.} \\
\text{| Possibility | Genotype | Phenotype |} \\
\text{|-------------|----------|----------------|} \\
\text{| 1 | BB | Brown Eyes |} \\
\text{| 2 | BB | Brown Eyes |} \\
\text{| 3 | Bb | Brown Eyes |} \\
\text{| 4 | Bb | Brown Eyes |} \\
\\
\text{2.} \\
\text{| Possibility | Genotype | Phenotype |} \\
\text{|-------------|----------|----------------|} \\
\text{| 1 | FF | Freckles |} \\
\text{| 2 | Ff | Freckles |} \\
\text{| 3 | Ff | Freckles |} \\
\text{| 4 | ff | No Freckles |} \\
\\
\text{3.} \\
\text{| Possibility | Genotype | Phenotype |} \\
\text{|-------------|----------|--------------------|} \\
\text{| 1 | Rr | Can Roll Tongue |} \\
\text{| 2 | Rr | Can Roll Tongue |} \\
\text{| 3 | Rr | Can Roll Tongue |} \\
\text{| 4 | Rr | Can Roll Tongue |} \\
\end{array}
}
\]