Explain how does the cell walls permit cells of fungi to withstand very dilute external media withou

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.