What is the function associated with the indicated neural activity?

This activity creates graded potentials in the plasma membrane of a postsynaptic cell. The graded potentials are changes in the membrane potential. These come in all sizes. A postsynaptic cell is a membrane that gets a signal from the presynaptic cell.

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.