Which of the following factor was used by Alfred Sturtevant to measure the distance between the genes and mapped their pasition on the chromosome

Options

A. Total recombination
B. Frequency of recombination
C. Parental gene combination
D. Nonparental combination

Answer

To solve the question regarding the factor used by Alfred Sturtevant to measure the distance between genes and map their positions on chromosomes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**: Alfred Sturtevant was a geneticist who contributed significantly to the field of genetics by developing methods to map genes on chromosomes.

2. **Identifying the Key Concept**: The key concept that Sturtevant used in his mapping technique was the frequency of crossing over, which is also known as recombination frequency.

3. **Explaining Crossing Over**: Crossing over occurs during meiosis when homologous chromosomes exchange genetic material. This process can lead to new combinations of alleles and is a crucial mechanism for genetic diversity.

4. **Linking Crossing Over to Gene Mapping**: Sturtevant proposed that the frequency of crossing over between two genes is proportional to the distance between them on a chromosome. The greater the distance, the higher the likelihood that crossing over will occur between those genes.

5. **Conclusion**: Therefore, the factor used by Alfred Sturtevant to measure the distance between genes and to map their positions on chromosomes is the frequency of crossing over (recombination frequency).

### Final Answer:
The factor used by Alfred Sturtevant to measure the distance between genes and map their positions on the chromosome is **frequency of crossing over**.

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