B3 – Exchange of materials What are diffusion, osmosis and active transport? Starter: A chip shop owner prepares his chips earlier in the day for the evening rush. He stores them in water until he needs to use them. What effect will this have on the chips?

Glossary Osmosis: the net movement of water from a high concentration of water to a low concentration of water. Diffusion: the net movement of particles from a high concentration to a low concentration. Active Transport: the movement of substances against a concentration gradient.

Osmosis Demo – visking tubing with sugar solution in. Sugar solution Strong Sugar Solution water

Osmosis and Diffusion Osmosis is the movement of WATER Diffusion is the movement of solutes. Key point: NO energy is needed.

What is a Concentration Gradient? Hills and graphs have gradients 1) which is the steepest gradient? 2) which move up a gradient and which move down a gradient?

moving down a concentration gradient Which way will the particles move?

Active transport This DOES Require energy Particles move against a concentration gradient. The energy is needed to make “pumps” move particles the wrong way. E.g. glucose from the intestine into the blood

Active Transport http://www.youtube.com/watch?v=1ZFqOvxXg9M&feature=related

moving UP or against a concentration gradient ENERGY The particles can move up the concentration gradient if energy is used This is active transport

Active Transport Active Transport

Active transport in plants

Active Transport Active transport occurs across semi permeable membranes and moves particles from a low concentration to a higher concentration. This is against the concentration gradient. Transport or carrier proteins are needed to get these molecules into the cells and these use energy. Cells that do active transport contain large numbers of mitochondria. Q: Where does the energy come from? Q: What do mitochondria do?

Active Transport Inside of cell Outside of cell ATP ADP P

Tasks Use the information to fill in the Venn diagram. To easy? Write a comparison of the 3 modes of transport.

Complete the past paper questions

Lumen of small Intestine Na+ high concentration Glucose Lumen of small Intestine Co Transport Na+ low concentration Glucose Epithelial Cell K+ Active Transport Facilitated Diffusion Blood Capillary Glucose K+

Plenary Make a list of similarities and differences between active transport and diffusion

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