Cross over frequency is proportional to

Options

A. Phenotypic recombinant frequency
B. Genotypic recombinant frequency
C. Haploid number of chromosomes
D. Diploid number of chromosomes

Answer

### Step-by-Step Solution:

1. **Understanding Crossover Frequency**:
- Crossover frequency refers to the rate at which crossover events occur between homologous chromosomes during meiosis. This process involves the exchange of genetic material between non-sister chromatids.

2. **Identifying the Result of Crossover**:
- The result of crossover is the formation of recombinant chromosomes, which leads to new genetic combinations or variations in the offspring.

3. **Defining Recombinant Frequency**:
- Recombinant frequency is defined as the percentage of offspring that exhibit recombinant phenotypes compared to the total number of offspring produced. It quantifies how often crossover events result in new genetic combinations.

4. **Establishing the Relationship**:
- The crossover frequency is directly proportional to the recombinant frequency. This means that as the crossover frequency increases, the recombinant frequency also increases, indicating a higher likelihood of producing recombinant phenotypes.

5. **Analyzing the Options**:
- Given the options:
- 1. Phenotypic recombinant frequency
- 2. Phenotypic recombinant frequency (repeated option)
- 3. Applied number of chromosomes
- 4. Diploid number of chromosomes
- The correct choice is the phenotypic recombinant frequency, as it reflects the observable traits resulting from the genetic recombination.

6. **Conclusion**:
- Therefore, the crossover frequency is proportional to the phenotypic recombinant frequency.