Crossing-over does not occur between any pair of homologous chromosomes during meiosis in male Drosophila. From what you have learned about meiosis and crossing-over, propose one hypothesis for why this might be the case.

There is no variation occurs in the offspring produce from male Drosophila.

Explanation: Crossing over is the key to variation in the organisms because parts of two different chromosomes are replaced with each other. This crossing over only exists in the sex cells or meiosis of cell division. In meiosis, the cell is divided into four daughter cells having half number of chromosome. These cells are not identical to each other due to crossing over.