Exchange Across Cell Membranes - Osmosis

Question 1

Define osmosis

Answer 1

Osmosis is the diffusion of water molecules across a partially permeable membrane, from an area of higher water potential to an area of lower water potential

Question 2

What is water potential?

Answer 2

Water potential is the potential of water molecules to diffuse out of or into a solution

Question 3

What has the highest water potential?

Answer 3

Pure water has the highest water potential. All solutions have a lower water potential than pure water

Question 4

What is it called when two solutions have the same water potential?

Answer 4

They’re isotonic

Question 5

Give three factors which the rate of osmosis depends on

Answer 5

1. The water potential gradient
2. The thickness of the exchange surface
3. The surface area of the exchange surface

Question 6

How does the water potential gradient affect the rate of osmosis?

Answer 6

The higher the water potential gradient, the faster the rate of osmosis. As osmosis takes place, the difference in water potential on either side of the membrane decreases, so the rate of osmosis levels off over time

Question 7

How does the thickness of the exchange surface affect the rate of osmosis?

Answer 7

The thinner the exchange surface, the faster the rate of osmosis

Question 8

How does the surface area affect the rate of osmosis?

Answer 8

The larger the surface area, the faster the rate of osmosis