5.5-Osmosis

Question 1

Define Water potential

Answer 1

• The pressure exerted by water molecules as they collide against each other or the container.
• It is measured in Pascals

Question 2

What is pure water?

Answer 2

Water potential of 0 kPa

Question 3

Effects of osmosis on animal cells

Answer 3

If solution is hypotonic (water moves in), animal cells face an increase in hydrostatic pressure. The cell then bursts. This is called cytolysis

If solution is hypertonic (water moves out), animal cells will lose water due to the concentration gradient, and the cell will undergo crenation

Question 4

Effects of osmosis on plant cells

Answer 4

If solution is hypotonic (water moves in), the hydrostatic pressure pushes the cell membrane to the cell wall. The turgid pressure stops water coming in and the cell becomes turgid

If solution is hypertonic (water moves out), water is lost and this leads to a reduction in the volume of the cytoplasm which pulls the cell membrane away from the cell wall causing the cell to be plasmolysed