Activity #11.Spray perfume at the back of the room and then move to the front of the room. 2.Observe for 2-3 minutes.

Activity #2 1.Fill a cup with water. Gently touch the surface of the water and taste the water. 2.Drop a sugar cube into the cup of water. 3.Taste the water after 10 minutes.

DIFFUSIONDIFFUSION

Learning ObjectivesAt the end of the lesson, you will be able to

• Define diffusion and explain its phenomenon

• Describe an example of diffusion in plants

• Describe an example of diffusion in animals

What happens during diffusion?

http://www.youtube.com/watch?v=WxfIDpset2I

Point A Point B

NET

B ADistance

Concentrationof particles

Particles diffuse down a concentration gradient

Direction of particle movement (net)

Concentration gradient: The difference in concentration between two regions

Point A Point B

The concentration of particles at point A and B have become the same.

There is no net movement of particles.

After some time… what will the concentration of particles at A

and B look like?

A small beaker of distilled water was placed on a bench. Using a pipette, a drop of iodine was placed at the bottom of the beaker. Explain why the water in the beaker was uniformly yellow after two hours.

There is a net movement of iodine molecules from where they are in a higher concentration which is at the bottom of the beaker to where they are in lower concentration which is the rest of the liquid in the beaker. Therefore, the iodine molecules spread out evenly after two hours.

After 2 hours

A small beaker of distilled water was placed on a bench. Using a pipette, a drop of iodine was placed at the bottom of the beaker. The beaker was uniformly yellow after two hours.

How can we increase the rate of diffusion in this case?

•By heating the beaker of water

Example of diffusion in animals:

Diffusion of oxygen from lungs to red blood cells.

Diffusion of carbon dioxide from blood to lungs.

Example of diffusion in plants:

Diffusion of carbon dioxide into the leaves of plants.

Diffusion of oxygen from lungs to red blood cells

Diffusion of carbon dioxide into the leaves of plants

DIFFUSIONDIFFUSION

What have we learnt in today’s lesson?

Definition: The net movement of particles down a concentration gradient

Atoms, ions or moleculesThe difference in concentration between two regions

Activity #11.Spray perfume at the back of the room and then move to the front of the room. 2.Observe for 2-3 minutes.

Activity #2 1.Fill a cup with water. Gently touch the surface of the water and taste the water. 2.Drop a sugar cube into the cup of water. 3.Taste the water after 10 minutes.

Explain what happened in…

Preparation for next lesson

Potato experiment!

1.Cut out a strip of potato2.Measure its length and breadth3.Soak it in tap water for 5 mins4.Measure its length and breadth again5.Soak it in saltish water for 5 mins6.Measure its length and breadth again7.Share findings with class!

Don’t be a !!!!