1. 1.7 Cells in their Environment Read p. 22 to 23. As you read, think about how nutrients enter cells.

2. Add “diffusion” to your vocabulary list.

3. Page WordDefinitionSketch or Example 23 DiffusionThe movement of molecules from an area of higher concentration to an area of lower concentration. Think of a waterfall: it moves from high to low.

4. Observe your teacher adding crystals of potassium permanganate to two beakers of water. What is the difference between the two beakers?

5. The purple colouring spreads out much more quickly in the beaker with the hot water because those molecules are moving faster, and experiencing more collisions. Diffusion happens more quickly when there is more energy in the system.

6. The teacher will squirt a spray of perfume at the front of the room. Raise your hand when you can smell it. Does diffusion occur through air as well as liquids?

7. Diffusion means… Spreading out This is one way nutrients can enter cells and Wastes can leave.

8. Molecules can enter and leave cells because of the… Pores in the cell membrane.

9. When something has pores, it is… “permeable.” Things can pass through it.

10. Add “selectively permeable” to your vocabulary list.

11. Page WordDefinitionSketch or Example 22 Selectively Permeable

12. Page WordDefinitionSketch or Example 22 Selectively Permeable Allowing certain things to enter or leave the cell. Based partly on size, but also on shape, and electric charge.

13. Observe the Demonstration: Can the salt crystals pass through: A. the glass? B. the fabric? C. the gauze?

14. Could it be possible to make the salt pass through the fabric? Dissolve the salt in water

15. Which of the “membranes” in the activity is most like a cell membrane.

16. How is a cell membrane even better than these materials?

17. A cell membrane can pull in needed molecules even if they seem to big to fit through the pore.

18. C.Y. U. p. 24 1,2,3,5 and 7. Use full sentences, indicating the question in the answer.