Osmosis

Question 1

Define osmosis

Answer 1

the passage of water from a region where it has a higher water potential to a region of lower water potential through a selectively permeable membrane.

Question 2

What is a solute?

Answer 2

substance dissolved in a solvent

Question 3

What is a solution?

Answer 3

solute and solvent

Question 4

What is the water potential of pure water?

Answer 4

0

Question 5

What happens to the water potential when solute is added to pure water?

Answer 5

It decreases

the more solute the more negative

Question 6

Describe the movement of solute and water/ explain how osmosis occurs

Answer 6

both solute and h20 moves in random motion due to kinetic energy

selectively permeable membrane only lets h20 across

h20 diffuses from x to y down the water potential gradient VIA OSMOSIS

when water potential on either side of the membrane is equal dynamic equilibrium is reached and there is no net movement of water.

Question 7

Describe osmosis in a animal cell when the water potential of the external solution is

i) higher
ii) equal
iiii) lower

Answer 7

i) the water potential of the external solution is higher than the cell solution so water enters cell which causes cell to swell and burst, releasing cell contents
ii) the water potential of the external solution is equal to the cell solution so water neither enters not exits the cell which causes no change
iii) the water potential of the external solution is lower than the cell solution so water leaves cell which causes cell to shrink

Question 8

Describe osmosis in a plant cell when the water potential is

i) higher
ii) equal
iiii) lower

Answer 8

i) the water potential of the external solution is higher than the cell solution so water enters cell which causes protoplast to swell and cell to go turgid, pushing the protoplast against the cell wall.
ii) the water potential of the external solution is equal to the cell solution so water neither enters not exits the cell which causes incipient plasmolysis
iii) the water potential of the external solution is lower than the cell solution so water leaves cell which causes protoplast to shrink and the cell to become plasmolysed