Osmosis

Question 1

Define osmosis

Answer 1

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

Question 2

What does selectively permeable mean?

Answer 2

membrane is permeable to water molecules but not larger molecules

Question 3

Define solute, solvent and solution

Answer 3

“solute - substance dissolved in a solvent
solvent - something a solute dissolves in
solution - solute and solvent together”

Question 4

What letter is water potential represented by?

Answer 4

Question 5

What are the units of water potential?

Answer 5

kPa (unit of pressure)

Question 6

What is water potential?

Answer 6

the pressure created by water molecules

Question 7

What is the water potential of pure water at standard temperature and pressure?

Answer 7

0kPa

Question 8

What happens to water potential when you add a solute to pure water?

Answer 8

it decreases

Question 9

What happens to the water potential as you add more solute?

Answer 9

it becomes more negative (lower)

Question 10

How can we find the water potential of cells or tissues?

Answer 10

place then in solutions of varying water potentials, when there is no net gain or loss of water the water potential in the cell must be equal to that in the external solution

Question 11

What causes water and solute molecules to be in random motion?

Answer 11

kinetic energy

Question 12

What is dynamic equilibrium?

Answer 12

water potential on either side of the plasma membrane are equal - there is no net movement of water

Question 13

Which of the following water potentials is the lowest? -23kPa, -56kPa, -45kPa

Answer 13

-56kPa

Question 14

Explain why a red blood cell placed in pure water will absorb water by osmosis

Answer 14

the water potential inside the cell is lower than the water potential outside the cell

Question 15

What name is given to a red cell bursting?

Answer 15

haemolysis

Question 16

How are animal cells prevented from bursting?

Answer 16

they are surrounded by liquid that has the same water potential as the cells

Question 17

What happens to an animal cell placed in a solution of lower water potential than itself?

Answer 17

water will leave and the cell will shrivel

Question 18

When a plant cell is placed in a higher water potential that the solution inside it becomes…

Answer 18

turgid

Question 19

When a plant cell is placed in a lower water potential that the solution inside it becomes…

Answer 19

plasmolysed