What is plasma membrane ? Describe it's semi-permeable nature.

Your friend Ishita is right. I would like to add few more points.


Cell membrane or plasma membrane is the outer most covering of the cell that separates the contents of the cell from its external environment. It is present in both animal and plant cells.

Functions of cell membrane:

  1. It gives definite shape to the cell.
  2. It is selectively permeable membrane.
  3. It separates the contents of cell from its surrounding medium.
  4. It regulates the movement of ions in an out of the cell.
  5. It provides mechanical barrier for the protection of the internal contents of the cell.


  • A semi permeable membrane is also called as a selectively permeable membrane.
  • This membrane is being permeable to only certain molecules and not to all molecules. That is, this membrane which allows the entry and exit of some materials in the cell but prevents the movement of some other substances. It is selectively permeable to ions and organic molecules and the movement of substances in and out of cells are controlled by plasma membrane.



@ Ishita: Good answer. Keep Posting!!

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plasma membrane is actually outer covering of the cell which seperates the contents of cell from outside (external environment). It is called semi-permeable because it  permits entry and exit of some materials in and out of cell while prevents the movement of some other.

Hope that it helps you.

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