10. Cell and cell organelles
1. Cell wall :
It Is the pound around the cell of algae, fungi and plants animal cell doesn't cell wall. it is an elastic and strong coat around cell membrane. it is mainly composed of carbohydrates like cellulose and pectin.
2.Plasma membrane :
plasma membrane is a thin ,fragile and elastic covering that separates the cell components from outer environment.
*It is known as selectively permeable membrane
# Function :-
- protein molecules are embedded in two layers of phospholipids.
- it allows some substance to enter the cell while prevents other substances.
- due to this property, useful molecules of water ,salt and oxygen enter the cell and carbon dioxide exists the cell.
* If any changes occur outside the cell, the cellular environment does not change due to plasma membrane. This condition is called Hemostasis.
3. Endocytosis :
A process by which cells absorb external material by engulfing it with the cell membrane is called Endocytosis .
4. Exocytosis :
Diffusion is the movement of a substance from an area of high concentration of the molecules to an area with a lower concentration.
* Entry or exit of small molecules like oxygen, carbon dioxide.
The travelling of water molecules across a semi - permeable membrane from a solution with a high concentration to a solution with a lower concentration.
7. Cytoplasm :
8. Cell Organelles :
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