What is a single celled organism absorbed by?

Single celled organisms or Unicellular does is they absorb pigments of sunlight.

Like for example algae is all around the world in waters they are single celled and absorb sunlight and do photosynthesis. 

For other organisms that have unicellular they also obtain O2 thru diffusion.

But in general mainly single celled org. do photosynthetic  

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.