What advantage does crossing over provide for organisms that undergo meiosis over those at only undergo mitosis throughout their life-cycle?

Crossing over is a complex mechanism which allows the exchange of the DNA sequence during meiosis.

Crossing over serves many purposes:

1. form genetically different daughter cells from parents.

2. leads to genetic diversity

3. leads to variation in the organism which proves useful.

The crossing over does not take place in the mitosis type of cell division which produces genetically similar daughter cells.