In a complimentary gene interaction calculate the number of phenotype and genotype produced in a cross AaBb `x` aaBB.

Options

A. 1 phenotype, 2 genotypes
B. 2 phenotypes, 4 genotypes
C. 4 phenotypes, 4 genotypes
D. 2 phenotypes, 2 genotypes

Answer

To solve the problem of calculating the number of phenotypes and genotypes produced in a cross of AaBb x aaBB, we will follow these steps:

### Step 1: Identify the Gametes
First, we need to determine the gametes produced by each parent.

- For the parent AaBb, the possible gametes are:
- AB
- Ab
- aB
- ab

- For the parent aaBB, the possible gametes are:
- aB
- aB (since both alleles for A are recessive, only aB can be produced)

### Step 2: Set Up the Punnett Square
Next, we can set up a Punnett square to visualize the combinations of these gametes.

| | aB | aB |
|---------|----------|----------|
| **AB** | AaBb | AaBb |
| **Ab** | Aabb | Aabb |
| **aB** | aaBb | aaBb |
| **ab** | aabb | aabb |

### Step 3: Determine the Genotypes
From the Punnett square, we can list the genotypes of the offspring:

1. AaBb (2 occurrences)
2. Aabb (2 occurrences)
3. aaBb (2 occurrences)
4. aabb (2 occurrences)

### Step 4: Count the Genotypes
Now, we count the unique genotypes:
- AaBb
- Aabb
- aaBb
- aabb

This gives us a total of **4 unique genotypes**.

### Step 5: Determine the Phenotypes
Next, we need to determine the phenotypes based on the dominant and recessive alleles:

- **AaBb**: Dominant phenotype (D)
- **Aabb**: Dominant phenotype (D)
- **aaBb**: Dominant phenotype (D)
- **aabb**: Recessive phenotype (r)

Thus, we have:
- Dominant phenotype (D): 3 occurrences (AaBb, Aabb, aaBb)
- Recessive phenotype (r): 1 occurrence (aabb)

### Step 6: Count the Phenotypes
This gives us a total of **2 unique phenotypes**:
1. Dominant phenotype
2. Recessive phenotype

### Final Answer
- **Number of Genotypes**: 4
- **Number of Phenotypes**: 2

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