In a cell undergoing meiosis, when a single crossover occurs between two genes of interest, the result is

The result is a recombination.

During meiosis, the homologous chromosomes that are paired side by side during phophase I, before being pulled apart by spindle fibres, can exchange genetic material in a process called crossing over
Sometimes when the homologous are pulled apart before the synapses process completes, one of the chromosomes may end up with a piece of the sister chromosome

Brother ur in collage do it yourself or i will tell prof. mike

They use the si unit, or metric system its all the same thing