The sexual cycle in fungi involves the three steps: The fusion of protoplasms between two motile or non-motile gametes is called plasmogamy.
Fusion of two nuclei called karyogamy.
Meiosis in zygote resulting in haploid spores.
Saprophytes feed on dead and decaying organisms. Fungi and many bacteria are saprobiotic.
Organisms like Nostoc, Anabaena have specialised heterocysts to fix atmospheric nitrogen.