Why does a hypotonic solution causes a cell to burst?

Answer 1

Hypotonic is a relative term i.e when you say a hypotonic(less concentration of electrolyte or solute in it) solution it is in comparision with other solution.

Here it is in comparision with the fluid of the cell.

As you say a hypotonic solution is around the cell here, therefore by the process of osmosis, fluid from the cell will drain out resulting it to shrink since solution travels from high concentration (cell) to lower concentration of solute(in hypotonic solution).

example: A grape kept in honey shrinks

Cell can swell and burst if there is a hypertonic solution around it. example: Raisin kept in water swells

Answer 2

Water enters the cell by osmosis in order to make the concentration on the inside the same as on the outside. If the hypotonic solution is pure water, an equilibrium can never be reached and water will keep entering the cell until so much pressure is built up that the cell bursts.

Answer 3

When a cell is exposed to hypotonic conditions, there is net water movement into the cell. Cells without walls will swell and may burst (lyse).