A cell wall is the outermost covering of a plant cell .
- It is made up of a substance called Cellulose .
- Cellulose gives it strength and rigidity .
- When fungi (and bacteria) are put into very dilute media . they tend to take up water from the outside and swell due to osmosis .
- A dilute medium is known as a hypotonic solution . It has a higher concentration of water than inside the cell .
- The swollen cell exerts a pressure against the cell wall , which exerts it back and keeps the cell in check due to its rigidity and hardness .
Hence, fungi are able to withstand very dilute media without bursting.