1. 1.4 Membrane Transport Skills:
Understanding:
Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport
The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis
Vesicles move materials within cells
Skills:
Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions
Applications:
Structure and function of sodium potassium pumps for active transport and potassium channels for facilitated diffusion in axons
Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis
Nature of science:
Experimental design: accurate quantitative measurements in osmosis experiments are essential

2. Movement across membranes
Endocytosis (1)
Exocytosis (2)
Simple diffusion (3)
Facilitated diffusion (4)
Active transport (5)
Osmosis (6)

3. Movement across membranes
Name of movement
How it works
Diagram/picture
Example of this movement
Create a presentation for your mode of movement (5 mins maximum)
To be presented on: Monday 29th October

4. Facilitated diffusion
Name of movement
How it works
Example
Drawing
Endocytosis
Exocytosis
Simple diffusion
Facilitated diffusion
Active Transport
Osmosis

5. Osmosis
Movement of water from a low solute concentration to a high solute concentration through a partially permeable membrane
Skills:
Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions

6. Hypotonic Solution Place a plant cell into pure water
Water goes down water potential gradient and into the cell by osmosis
Will not continue to absorb water until it bursts
Strong cellulose walls
Cell will gain mass
Skills:
Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions

7. Hypertonic Solution Place a plant cell into salt water
Water lost from the cell
Water goes down water potential gradient out of the cell by osmosis
Cell loses turgidity
If it continues = cytoplasm and vacuole shrink
Cell will lose mass
Skills:
Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions

8. Label your diagrams What is happening? Which direction is water moving
Why?
What type of solution are each of these cells in?

9. Prescribed Practical
Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions
Skills:
Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions

10. Prescribed Practical From your raw data
Find the percentage change in mass
Plot a scatter graph of solute concentration vs. % change in mass (there will be a negative Y axis as well)
Draw a line of best fit
What is the osmolarity of the potato
(where does your line of best fit meet the X axis?)
Skills:
Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions