explain how the jellyfish follows alternation of generation in it's life cycle.?

Answer 1

You probably have a diagram of the jellyfish life cycle in your textbook, but here is another view. http://www.mdsg.umd.edu/MarineNotes/Jul-Aug94/

Just search "aurelia life cycle" in images.

The jellyfish form we think of are the adults. They reproduce sexually, making eggs and sperms. The resulting larva is called a planula. The planula swims around, finds a good place to grow, and settles down to grow into a polyp. The polyp grows and begins to make layers of buds (like a stack of coffee filters or a stack of thin paper plates). This is the part of the life cycle which is asexual. The layers peel off, flip over, and swim away to grow into the adult sexual form of the jellyfish.