How many types of zygotic combinations are possible between a cross AaBBCcDd × AAbbCcDD?

Options

A. 32
B. 128
C. 64
D. 16

Answer

To determine the number of zygotic combinations possible from the cross AaBBCcDd × AAbbCcDD, we can follow these steps:

### Step 1: Identify the Genotypes
The genotypes of the parents are:
- Parent 1: AaBBCcDd
- Parent 2: AAbbCcDD

### Step 2: Determine the Number of Heterozygous Alleles
Count the number of heterozygous alleles (represented by 'A' or 'a', 'C' or 'c', 'D' or 'd') in each parent:
- Parent 1 (AaBBCcDd):
- Heterozygous alleles: A/a (1), C/c (1), D/d (1) → Total = 3 heterozygous alleles
- Parent 2 (AAbbCcDD):
- Heterozygous alleles: A/a (1), C/c (1) → Total = 2 heterozygous alleles

### Step 3: Calculate the Number of Gametes for Each Parent
The number of possible gametes can be calculated using the formula \(2^n\), where \(n\) is the number of heterozygous alleles:
- For Parent 1:
- Number of gametes = \(2^3 = 8\)
- For Parent 2:
- Number of gametes = \(2^1 = 2\)

### Step 4: Calculate the Total Number of Zygotic Combinations
The total number of zygotic combinations is the product of the number of gametes from each parent:
- Total zygotic combinations = Number of gametes from Parent 1 × Number of gametes from Parent 2
- Total zygotic combinations = \(8 \times 2 = 16\)

### Final Answer
Thus, the total number of zygotic combinations possible from the cross AaBBCcDd × AAbbCcDD is **16**.

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