Question 1 Page 61 - Chapter 5 Class 9 - The Fundamental Unit of Life

How do substances like CO 2 and water move in and out of the cell? Discuss.

Answer:

Cells have a semi-permeable membrane (cell membrane) as the outer covering. 

• Substances inside the cell and those in the surroundings can move from areas of high concentration to areas of low concentration .

CO 2 as well as water follow this principle.

• If an animal or plant cell is put in water, water will move across the walls of the cell. 
• If the water content is higher outside the cell than inside it , water will move into the cell, thus causing it to swell up.
• If the water content is higher inside the cell than outside it , water will move from the cell into the surrounding, thus causing it to shrivel up.
• Similarly, CO 2 can also move in and ou t of a cell.
• The process by which it happens is called diffusion .