Diffusion and Osmosis:-
The plasma membrane, also called as cell membrane as it is works as a barrier between the inner and outer surface of a cell. In animal cells, the plasma membrane is present in the outer most layer of the cell and in plant cell it is present just beneath the cell wall. This is a semipermeable membrane that only allows certain substances to pass through it. This is related to diffusion and osmosis, but first lets try and understand these terms. Diffusion is the process where particles move from an area of high concentration to an area of low concentration. Osmosis can be described as the process where water moves from an area of low solute concentration to a solution with a high solute concentration. Osmosis is a special type of diffusion in a way, it can be described as diffusion across a semipermeable membrane. Another similarity between diffusion and osmosis is they are both mediums of passive transport. There are three states of solutions; isotonic(equal solutes on both sides), hypertonic( there are more solute molecules outside the cell) and hypotonic(more salt molecules on the inside of the cell). A diagram on the right helps us visualise these states. Plants receive water to carryout photosynthesis through the process of osmosis,as established before this process is highly important and all life on earth ultimately rely on producers for energy.
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