Here's why:

* Meiosis is a type of cell division that reduces the number of chromosomes in a cell by half. This is crucial for sexual reproduction because it ensures that offspring inherit one set of chromosomes from each parent.

* Mitosis produces identical daughter cells with the same number of chromosomes as the parent cell. This is important for growth and repair, but it doesn't create the genetic diversity needed for sexual reproduction.

In fungi, the life cycle often involves a haploid stage (with one set of chromosomes) and a diploid stage (with two sets of chromosomes). Meiosis occurs in the diploid stage to produce haploid spores, which then develop into haploid gametes. The fusion of two gametes (fertilization) creates a diploid zygote that can undergo mitosis to grow into a new fungal organism.