Find the incorrect statement w.r.t chromosomal mapping

Options

A. Crossing over is important in locating genes on chromosome
B. Crossing over is important in locating genes on chromosome
C. Recombination frequency is inversely proportional to distance between genes
D. The sequences and the relative distance between various genes is graphically represented in terms of recombina tion frequencies

Answer

To find the incorrect statement with respect to chromosomal mapping, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Chromosomal Mapping**: Chromosomal mapping involves determining the positions of genes on a chromosome and the distances between them. This is important for understanding genetic linkage and recombination.

2. **Analyzing Option 1**:
- Statement: "Crossing over is important in locating genes on Chromosome."
- Evaluation: This statement is correct. Crossing over during meiosis allows for the exchange of genetic material between homologous chromosomes, which helps in mapping the location of genes.

3. **Analyzing Option 2**:
- Statement: "Crossing over is important in locating genes on Chromosome."
- Evaluation: This statement is identical to Option 1 and is also correct for the same reasons.

4. **Analyzing Option 3**:
- Statement: "The combination frequency is inversely proportional to the distance between genes."
- Evaluation: This statement is incorrect. The recombination frequency is actually directly proportional to the distance between genes. As the distance increases, the likelihood of recombination also increases, making this statement false.

5. **Analyzing Option 4**:
- Statement: "The sequences and the relative distance between various genes is graphically represented in terms of recombination frequency."
- Evaluation: This statement is correct. Geneticists often use recombination frequency to create genetic maps that show the relative positions of genes on a chromosome.

### Conclusion:
The incorrect statement with respect to chromosomal mapping is **Option 3**: "The combination frequency is inversely proportional to the distance between genes."

---