scientists can test differences of the area with pigmentation by observing which is lighter and which is darker however they use microscope to look the difference of the pigmentation over the cells.
As long as you are referring to the green plants aka producers of the food chain/web.
Osmosis of Water Across the Membrane. Osmosis is the tendency for water molecules to move from where there is a higher concentration to where there is a lower one. ... The cell membrane helps to regulate and slow down the flow of water into the cell. This is yet another way that the cell membrane helps maintain homeostasis
