Question

which part of the plant cell permits it to withstand very dillute external medium without brusting

Answer 1

In a very dilute medium the cells  take up water by osmosis. The cell swells, building up pressure against the cell wall. The wall exerts an equal pressure against the swollen cell. Thus due to the equal pressure from both the sides, the cells of fungi can withstand very dilute external media without bursting

Answer 2

cell wall permits plant cell to withstand very dilute external medium without brusting