A cross between AaBB X aa BB yields a genotypic ratio of :-

Options

A. 1 AaBB: 1 aaBB
B. 1 AaBB : 3 aaBB
C. 3AaBB: 1 aa BB
D. All AaBB

Answer

To solve the problem of determining the genotypic ratio from the cross AaBB x aabb, we will follow these steps:

### Step 1: Identify the Genotypes of the Parents
The two parents in the cross are:
- Parent 1: AaBB
- Parent 2: aabb

### Step 2: Determine the Gametes Produced by Each Parent
Next, we need to find out the gametes that each parent can produce:
- Parent 1 (AaBB) can produce two types of gametes:
- AB (from A and B)
- aB (from a and B)

- Parent 2 (aabb) can only produce one type of gamete:
- ab (from a and b)

### Step 3: Set Up the Punnett Square
Now, we can set up a Punnett square to visualize the potential offspring from the cross:

```
ab
__________
AB | AaBb |
|__________|
aB | aaBb |
|__________|
```

### Step 4: Determine the Offspring Genotypes
From the Punnett square, we can see the following genotypes of the offspring:
1. AaBb (from AB and ab)
2. aaBb (from aB and ab)

### Step 5: Count the Genotypes
Now, we count the number of each genotype:
- AaBb: 1
- aaBb: 1

### Step 6: Write the Genotypic Ratio
The genotypic ratio of the offspring is:
- 1 AaBb : 1 aaBb

### Final Answer
Thus, the genotypic ratio from the cross AaBB x aabb is **1:1**.

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