Some plants respond to light with a sudden enlargement of their leaf pores. this response is important because it enables the plant to increase its intake of

This response is important because it enables the plant to increase its intake of carbon dioxide. Carbon dioxide  is an important gas,during the process of photosynthesis, where plants use energy from sunlight to make simple sugars and release oxygen. This is also a way of absorbing carbon dioxide (a green house gas) from the atmosphere thus reducing its amounts.

Called for 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.