NCERT Solutions for Class 9th Biology : Chapter Fundamental Unit of Life Exercise 61

Discussion in 'CBSE Class 9 Natural Science Help' started by saralas, May 17, 2014.

  1. saralas

    saralas Member

    How do substances like CO2 and water move in and out of the cell? Discuss

    Substances like CO2 move in and out of the cell by the process of diffusion. When the concentration of CO2 accumulates in the cell and is higher than the cell's external environment, it moves out and is thus excreted. Similarly, when its concentration is lower in the cell as compared to outside the cell, it moves into the cell.
    Water also moves in and out of the cell by the same principle of difference of concentration, but the process through which water moves across a selectively permeable membrane is called osmosis.

    Concept insight: Osmosis is a special type of diffusion in which movement of water takes place through semi permeable membrane whereas in diffusion movement of molecules takes place without a semi permeable membrane.

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