Why are there many separate ecosystems in a rainforest

Why is it important to reduce the number of chromosomes in half when forming gametes for sexual reproduction?

This is the main structural axis of the plant that supports leaves, flowers and fruits; transports fluids; stores nutrients and produces new tissue.

In pea plants, yellow seed color (y) is dominant and green seed color (y) is recessive. based on the punnett squares, what are the chances that the offspring in the second generation will have green seeds?