Point source means: the pollution that comes from a single point (examples)
Sewage pipes releasing sewage into a ditch
Smokestack style factory chimneys
Oil pipes
Pollution which is caused by rain fall or snow melting into the ground. As the runoff moves, it picks up and carries away natural and human made pollutants, Finally reaching a lake, river, ocean, groundwater.
Submerging a plant cell in distilled water (100% water) will result in turgid plant cell.
When the plant cell is placed in distilled water which is a hypotonic solution , it takes up water by osmosis and starts to swell. Because plant cell has the cell wall bursting is prevented. As a result, he plant cell is said to have become "turgid" (i.e. swollen and hard).
Water then moves from cell to cell through the root cortex by osmosisalong a concentration gradient; this means that each cell is hypertonic to the one before it. In the centre of the root the water enters the xylem vessels. Water may move by diffusionthrough the cell walls and intercellular spaces.