Mendelian Genetics Worksheet featuring Punnett squares for analyzing genetic crosses involving homozygous dominant, heterozygous, and homozygous recessive parents.

Problem Overview:

The task involves completing Punnett squares for various genetic crosses and determining the genotype ratios and phenotype ratios of the offspring. The crosses involve alleles for a trait where:
- A represents the dominant allele.
- a represents the recessive allele.

We will solve each cross step by step, filling in the Punnett squares and calculating the ratios.

---

Crosses with one homozygous dominant parent:

#### 1. AA x AA
- Punnett Square:
```
A A
A AA AA
A AA AA
```
- Offspring Genotypes: All are AA.
- Genotype Ratio: 4 AA (100%)
- Phenotype Ratios:
- Dominant: 4 (100%)
- Recessive: 0 (0%)

#### 2. AA x Aa
- Punnett Square:
```
A a
A AA Aa
A AA Aa
```
- Offspring Genotypes: AA, AA, Aa, Aa.
- Genotype Ratio: 2 AA : 2 Aa (1:1)
- Phenotype Ratios:
- Dominant: 4 (100%)
- Recessive: 0 (0%)

#### 3. AA x aa
- Punnett Square:
```
A A
a Aa Aa
a Aa Aa
```
- Offspring Genotypes: All are Aa.
- Genotype Ratio: 4 Aa (100%)
- Phenotype Ratios:
- Dominant: 4 (100%)
- Recessive: 0 (0%)

---

Crosses with one heterozygous parent:

#### 4. Aa x AA
- Punnett Square:
```
A A
a Aa Aa
a Aa Aa
```
- Offspring Genotypes: All are Aa.
- Genotype Ratio: 4 Aa (100%)
- Phenotype Ratios:
- Dominant: 4 (100%)
- Recessive: 0 (0%)

#### 5. Aa x Aa
- Punnett Square:
```
A a
A AA Aa
a Aa aa
```
- Offspring Genotypes: AA, Aa, Aa, aa.
- Genotype Ratio: 1 AA : 2 Aa : 1 aa (1:2:1)
- Phenotype Ratios:
- Dominant: 3 (75%)
- Recessive: 1 (25%)

#### 6. Aa x aa
- Punnett Square:
```
A a
a Aa aa
a Aa aa
```
- Offspring Genotypes: Aa, Aa, aa, aa.
- Genotype Ratio: 2 Aa : 2 aa (1:1)
- Phenotype Ratios:
- Dominant: 2 (50%)
- Recessive: 2 (50%)

---

Crosses with one homozygous recessive parent:

#### 7. aa x AA
- Punnett Square:
```
A A
a Aa Aa
a Aa Aa
```
- Offspring Genotypes: All are Aa.
- Genotype Ratio: 4 Aa (100%)
- Phenotype Ratios:
- Dominant: 4 (100%)
- Recessive: 0 (0%)

#### 8. aa x Aa
- Punnett Square:
```
A a
a Aa aa
a Aa aa
```
- Offspring Genotypes: Aa, Aa, aa, aa.
- Genotype Ratio: 2 Aa : 2 aa (1:1)
- Phenotype Ratios:
- Dominant: 2 (50%)
- Recessive: 2 (50%)

#### 9. aa x aa
- Punnett Square:
```
a a
a aa aa
a aa aa
```
- Offspring Genotypes: All are aa.
- Genotype Ratio: 4 aa (100%)
- Phenotype Ratios:
- Dominant: 0 (0%)
- Recessive: 4 (100%)

---

Final Answer:

Summarizing all the results:

| Cross | Genotype Ratio | Phenotype Ratio |
|------------------|----------------|-----------------|
| AA x AA | 4 AA | 4 Dominant |
| AA x Aa | 2 AA : 2 Aa | 4 Dominant |
| AA x aa | 4 Aa | 4 Dominant |
| Aa x AA | 4 Aa | 4 Dominant |
| Aa x Aa | 1 AA : 2 Aa : 1 aa | 3 Dominant : 1 Recessive |
| Aa x aa | 2 Aa : 2 aa | 2 Dominant : 2 Recessive |
| aa x AA | 4 Aa | 4 Dominant |
| aa x Aa | 2 Aa : 2 aa | 2 Dominant : 2 Recessive |
| aa x aa | 4 aa | 4 Recessive |

$$
\boxed{\text{See detailed explanation above for each Punnett square and ratio.}}
$$