1. Diffusion, Osmosis and Active Transport
Grade Ten – BGCSE Biology
Movement in and out of cells

2. Order of Presentation Movement in and out of cells
Definition of diffusion
Examples of diffusion
Definition of Osmosis
Examples of Osmosis
Definition of Active Transport
Examples of Active Transport

3. Particles of oxygen, carbon dioxide, glucose and water are always in motion.

4. An example of diffusion

5. Concentration gradient
A difference in concentration of molecules in physical space is called a concentration gradient.

6. Movement of Particles

7. Diffusion
Movement of particles from an area of high concentration to an area of low concentration.

8. Osmosis
Dilute solution
Concentrated solution
Movement of water from a dilute solution to a concentrated solution across a partially permeable membrane.

9. Plant cells in solution
How does the water move?

10. Turgid and flaccid
How did the cells become i) flaccid and ii) turgid?

12. Red blood cells in solutions – animal cell
In concentrated solution
In dilute solution
Same concentration

13. What kind of solution is found in Beaker A, B and C
What kind of solution is found in Beaker A, B and C? How does this affect the red blood cell?

14. Across a semi-permeable membrane

15. Concentration same on both sides of semi-permeable membrane

16. Paramecium
Contractile vacuole which balances water in aquatic environment.

17. Ileum of the small intestine

18. Active Transport
Cell membrane
is the movement of molecules across a cell membrane in the direction against the concentration gradient and requires energy from the cell.

19. Active Transport
Cell membrane
Happens when the cell has special receptors for materials needed by the cell, even though the cell already has a high concentration of the material.
Materials are brought in by the cell.

22. 1. Why does oxygen enter the red blood cell?
Review
1. Why does oxygen enter the red blood cell?

23. There is more oxygen outside the cell than inside the cell
So oxygen diffuses into the cell

24. Root Hair Cell
Minerals diffuse into root hair cell, then water by osmosis and finally by active transport any other minerals that might be present.

25. 2. How do diffusion, osmosis and active transport differ?

26. Summary
Materials needed by cells move into the cell first by diffusion, water moves by osmosis and finally by active transport.
Diffusion and osmosis do not require energy by the cell and are along the concentration gradient.
Active transport involves movement against the concentration gradient and requires energy.