a prey population consists of individuals with a variety of running speeds. The adaption that allows some of these animals to run fast would be an example of natural selection if it helps them

Closing a ring restricts the rotation around individual car bon carbon bonds hope it will you !

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.