Mendelian Genetics Worksheet featuring Punnett squares for various genetic crosses involving dominant and recessive alleles.

Absolutely! Let’s walk through each Punnett square step by step, filling in the genotypes and phenotypes based on Mendelian genetics. We’ll assume “A” is the dominant allele and “a” is the recessive allele.

---

## ✔ Crosses with one homozygous dominant parent:

1. AA × AA

```
| A | A
----|-----|----
A | AA | AA
A | AA | AA
```
- Offspring Genotypes: All AA → AA = 4/4, Aa = 0, aa = 0
- Offspring Phenotypes: All Dominant (since AA expresses dominant trait) → Dominant = 4/4, Recessive = 0

---

2. AA × Aa

```
| A | A
----|-----|----
A | AA | AA
a | Aa | Aa
```
- Offspring Genotypes: AA = 2/4, Aa = 2/4, aa = 0 → AA = 1/2, Aa = 1/2, aa = 0
- Offspring Phenotypes: All Dominant (both AA and Aa show dominant phenotype) → Dominant = 4/4, Recessive = 0

---

3. AA × aa

```
| A | A
----|-----|----
a | Aa | Aa
a | Aa | Aa
```
- Offspring Genotypes: All Aa → AA = 0, Aa = 4/4, aa = 0
- Offspring Phenotypes: All Dominant (Aa shows dominant trait) → Dominant = 4/4, Recessive = 0

---

## ✔ Crosses with one heterozygous parent:

4. Aa × AA

*(Same as #2 above — just order swapped)*
```
| A | a
----|-----|----
A | AA | Aa
A | AA | Aa
```
- Offspring Genotypes: AA = 2/4, Aa = 2/4, aa = 0 → AA = 1/2, Aa = 1/2, aa = 0
- Offspring Phenotypes: All Dominant → Dominant = 4/4, Recessive = 0

---

5. Aa × Aa

*(Classic monohybrid cross)*
```
| A | a
----|-----|----
A | AA | Aa
a | Aa | aa
```
- Offspring Genotypes: AA = 1/4, Aa = 2/4, aa = 1/4 → AA = 1/4, Aa = 1/2, aa = 1/4
- Offspring Phenotypes: Dominant = AA + Aa = 3/4, Recessive = aa = 1/4 → Dominant = 3/4, Recessive = 1/4

---

6. Aa × aa

```
| A | a
----|-----|----
a | Aa | aa
a | Aa | aa
```
- Offspring Genotypes: Aa = 2/4, aa = 2/4 → AA = 0, Aa = 1/2, aa = 1/2
- Offspring Phenotypes: Dominant = Aa = 2/4, Recessive = aa = 2/4 → Dominant = 1/2, Recessive = 1/2

---

## ✔ Crosses with one homozygous recessive parent:

7. aa × AA

*(Same as #3 above — order swapped)*
```
| a | a
----|-----|----
A | Aa | Aa
A | Aa | Aa
```
- Offspring Genotypes: All Aa → AA = 0, Aa = 4/4, aa = 0
- Offspring Phenotypes: All Dominant → Dominant = 4/4, Recessive = 0

---

8. aa × Aa

*(Same as #6 above — order swapped)*
```
| a | a
----|-----|----
A | Aa | Aa
a | aa | aa
```
- Offspring Genotypes: Aa = 2/4, aa = 2/4 → AA = 0, Aa = 1/2, aa = 1/2
- Offspring Phenotypes: Dominant = 1/2, Recessive = 1/2

---

9. aa × aa

```
| a | a
----|-----|----
a | aa | aa
a | aa | aa
```
- Offspring Genotypes: All aa → AA = 0, Aa = 0, aa = 4/4
- Offspring Phenotypes: All Recessive → Dominant = 0, Recessive = 4/4

---

## 📝 Final Answers to Fill In:

---

Crosses with one homozygous dominant parent:

#### AA × AA
- Offspring Genotypes: AA = 4/4, Aa = 0, aa = 0
- Offspring Phenotypes: Dominant = 4/4, Recessive = 0

#### AA × Aa
- Offspring Genotypes: AA = 2/4, Aa = 2/4, aa = 0
- Offspring Phenotypes: Dominant = 4/4, Recessive = 0

#### AA × aa
- Offspring Genotypes: AA = 0, Aa = 4/4, aa = 0
- Offspring Phenotypes: Dominant = 4/4, Recessive = 0

---

Crosses with one heterozygous parent:

#### Aa × AA
- Offspring Genotypes: AA = 2/4, Aa = 2/4, aa = 0
- Offspring Phenotypes: Dominant = 4/4, Recessive = 0

#### Aa × Aa
- Offspring Genotypes: AA = 1/4, Aa = 2/4, aa = 1/4
- Offspring Phenotypes: Dominant = 3/4, Recessive = 1/4

#### Aa × aa
- Offspring Genotypes: AA = 0, Aa = 2/4, aa = 2/4
- Offspring Phenotypes: Dominant = 2/4, Recessive = 2/4

---

Crosses with one homozygous recessive parent:

#### aa × AA
- Offspring Genotypes: AA = 0, Aa = 4/4, aa = 0
- Offspring Phenotypes: Dominant = 4/4, Recessive = 0

#### aa × Aa
- Offspring Genotypes: AA = 0, Aa = 2/4, aa = 2/4
- Offspring Phenotypes: Dominant = 2/4, Recessive = 2/4

#### aa × aa
- Offspring Genotypes: AA = 0, Aa = 0, aa = 4/4
- Offspring Phenotypes: Dominant = 0, Recessive = 4/4

---

✔ You can now fill in your worksheet with these values. Each box in the Punnett square corresponds to one offspring genotype, and ratios are based on 4 total offspring per cross.

Let me know if you’d like this in a printable table format or with visual diagrams!