Enzyme decreases or stops the synthesis of an enzyme when the enzyme is not needed, whereas enzyme initiates the synthesis of an enzyme only when it is needed (the substrate is present).

Iguess i would say diagrams would be most difficult subject too correct

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.

Ican not answer this question since it does not have enough information