How many non-parental gene combinations were obtained when Morgan crossed yellow bodied, white eyed female to brown bodied, red eyed male ?

Options

A. `1.3%`
B. `37.2%`
C. `98.7%`
D. `62.8%`

Answer

To solve the question of how many non-parental gene combinations were obtained when Morgan crossed a yellow-bodied, white-eyed female Drosophila with a brown-bodied, red-eyed male, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Traits and Genotypes**:
- The traits involved are body color and eye color.
- The yellow body (Y) and white eyes (w) are recessive traits, while brown body (B) and red eyes (R) are dominant traits.
- Therefore, the genotypes can be represented as:
- Yellow-bodied, white-eyed female: **yyww**
- Brown-bodied, red-eyed male: **BbRr** (assuming he is heterozygous for both traits)

2. **Perform the Cross**:
- When we cross these two flies, we need to consider the gametes produced by each parent.
- The yellow-bodied, white-eyed female can only produce gametes with the alleles **yw**.
- The brown-bodied, red-eyed male can produce gametes with combinations of his alleles: **BR, Br, bR, br**.

3. **Determine Offspring Combinations**:
- The offspring combinations can be formed by combining the female's gamete (yw) with each of the male's gametes:
- yw + BR = yB R (yellow-bodied, red-eyed)
- yw + Br = yB r (yellow-bodied, white-eyed)
- yw + bR = yb R (brown-bodied, red-eyed)
- yw + br = yb r (brown-bodied, white-eyed)

4. **Identify Parental and Non-parental Combinations**:
- The parental combinations are:
- Yellow-bodied, white-eyed (yw)
- Brown-bodied, red-eyed (BR)
- The non-parental (recombinant) combinations are:
- Yellow-bodied, red-eyed (yB R)
- Brown-bodied, white-eyed (yb r)

5. **Calculate Non-parental Combinations**:
- In Morgan's experiment, it was found that the majority of offspring were of parental type (98.7%), while only a small percentage (1.3%) were of recombinant type.
- Therefore, the number of non-parental gene combinations (recombinant types) obtained from this cross is **1.3%**.

### Final Answer:
The number of non-parental gene combinations obtained from the cross is **1.3%**.

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