When AABBcc is crossed with AaBbCc then the ratio of hybrid for all the three genes is :-

Options

A. `1//8`
B. `1//4`
C. `1//16`
D. `1//32`

Answer

To solve the problem of determining the ratio of hybrids for all three genes when AABBcc is crossed with AaBbCc, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes of Parents:**
- Parent 1: AABBcc (homozygous for A and B, homozygous recessive for c)
- Parent 2: AaBbCc (heterozygous for all three genes)

2. **Analyze Each Gene Independently:**
- According to Mendel's law of independent assortment, we can analyze each gene separately.

3. **Gene A Analysis:**
- From Parent 1 (AABBcc), the only allele for gene A is A (homozygous).
- From Parent 2 (AaBbCc), the alleles for gene A are A and a (heterozygous).
- Possible offspring combinations for gene A:
- A (from AABBcc) and A (from AaBbCc) → AA
- A (from AABBcc) and a (from AaBbCc) → Aa
- Ratio of hybrids (Aa) to homozygous (AA):
- 1 AA : 1 Aa → The frequency of Aa is 1/2.

4. **Gene B Analysis:**
- From Parent 1 (AABBcc), the only allele for gene B is B (homozygous).
- From Parent 2 (AaBbCc), the alleles for gene B are B and b (heterozygous).
- Possible offspring combinations for gene B:
- B (from AABBcc) and B (from AaBbCc) → BB
- B (from AABBcc) and b (from AaBbCc) → Bb
- Ratio of hybrids (Bb) to homozygous (BB):
- 1 BB : 1 Bb → The frequency of Bb is 1/2.

5. **Gene C Analysis:**
- From Parent 1 (AABBcc), the only allele for gene C is c (homozygous recessive).
- From Parent 2 (AaBbCc), the alleles for gene C are C and c (heterozygous).
- Possible offspring combinations for gene C:
- c (from AABBcc) and C (from AaBbCc) → Cc
- c (from AABBcc) and c (from AaBbCc) → cc
- Ratio of hybrids (Cc) to homozygous recessive (cc):
- 1 Cc : 1 cc → The frequency of Cc is 1/2.

6. **Calculate Overall Hybrid Ratio:**
- Since the genes assort independently, we multiply the frequencies of hybrids for each gene:
- Frequency of Aa = 1/2
- Frequency of Bb = 1/2
- Frequency of Cc = 1/2
- Overall frequency of hybrids (AaBbCc) = (1/2) × (1/2) × (1/2) = 1/8.

### Final Answer:
The ratio of hybrids for all three genes (AaBbCc) is **1/8**.

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