1. Exchange with the Environment Mod.A U.1 L.5
Cells in Action
Exchange with the Environment
Mod.A U.1 L.5

2. Types of Cell Transport
Passive Transport – Diffusion
- Osmosis
Active Transport – Endocytosis
- Exocytosis
- Active Uptake

3. Passive Transport No energy needed
Particles move along a concentration gradient
In cells small particles easily move across the cell membrane e.g oxygen, CO2
Particles move from areas of high concentration to areas of low concentration
Larger molecules move through protein channels , e.g. glucose

4. Diffusion Occurs with solids, liquids or gases
Particles travel from areas that are crowded into areas that aren’t
High to Low concentration
Happens in cells: inside and out

6. Demonstrations of Diffusion
Perfume or room deodorizer
Food coloring
Cotton ball in plastic container
Cell projects
This type of particle movement requires NO energy

7. Factors affecting Diffusion
1. Temperature
2. Size of particles
3. Concentration Gradient
Factors affecting Diffusion

8. Osmosis A special kind of diffusion The diffusion of water molecules
Always happens through a semi-permeable membrane
Only water molecules involved

9. When the molecules are evenly distributed throughout a space - it is called EQUILIBRIUM

10. Demonstrations of Osmosis
The Greedy Grape
The Iodine into a starch solution
Potatoes in distilled water
Celery sticks
(Draw diagrams of each demo)

11. In Cells The cell membrane
Is semi-permeable, bi-lipid
Controls what enters and leaves cell

12. Vocabulary Isotonic: Same concentration – in equilibrum
Hypertonic: Higher concn. of solute
Hypotonic: Lower concn. of solute

13. Active Transport Energy needed
Moves across a membrane against a concentration gradient
From area of LOW concentration to areas of higher concentration
2 main types:
Transport Proteins
Endocytosis / Exocytosis

14. Transport Proteins
Proteins in cell membrane use energy to pick up and carry molecules across the membrane
e.g calcium, sodium, potassium,

15. 2. Endocytosis and Exocytosis

16. Endocytosis – Solids
Phagocytosis - Liquids

17. Answer these Questions in your ntbk.
Describe 3 methods by which substances can move into and out of the cells
How are passive transport and active transport similar? How are they different?
Why is small size an advantage to a cell?
Thinking Critically – Predicting.
A single celled organism is transferred from a tank of fresh water into a tank of salt water. How will the cell change? Explain.