What shall be ratio in offspring when a roan cow is crossed with a white bull:-

Options

A. `1:2:1`
B. `3:1`
C. `1:1`
D. All roan

Answer

To solve the problem of determining the offspring ratio when a roan cow is crossed with a white bull, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Alleles**:
- The coat color in cows is determined by two alleles: one for red (R) and one for white (W).
- The roan color is a result of the co-dominance of these alleles, represented as RW.

2. **Determine the Genotypes**:
- The roan cow has the genotype RW (heterozygous).
- The white bull has the genotype WW (homozygous).

3. **Gamete Formation**:
- The roan cow (RW) can produce two types of gametes: R and W.
- The white bull (WW) can only produce one type of gamete: W.

4. **Set Up the Punnett Square**:
- Create a Punnett square to visualize the potential offspring:
```
W | W
----------------
R | RW | RW
----------------
W | WW | WW
```

5. **Analyze the Offspring**:
- From the Punnett square, we see the possible genotypes of the offspring:
- 2 RW (roan)
- 2 WW (white)

6. **Calculate the Ratio**:
- The ratio of the offspring is:
- 1 RW (roan) : 1 WW (white)
- Therefore, the final ratio of the offspring is 1:1.

### Final Answer:
The ratio in the offspring when a roan cow is crossed with a white bull is **1:1**.

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