Chapter 11 Movement of Substances

1. Chapter 11 Movement of Substances

2. Explain the role of selectively permeable membranes. Define the terms: osmosis & diffusion Give examples of diffusion and osmosis. Define the term: turgor. Explain turgidity in plant cells. Describe the application of high salt or sugar concentration in food preservation. Syllabus

3. The Cell

6. Cell membrane is the boundary between inside & outside…separates cell from its environment Can it be an impenetrable boundary? NO! IN food carbohydrates sugars, proteins amino acids lipids salts, O2,H2O OUT waste ammonia salts CO2 H2O products OUT IN cell needs materials in & products or waste out

7. Membranes can be Permeable – let everything in and out Semi Permeable - let some things in and out Impermeable – let nothing in and out Permeability

8. Homeostasis – Maintaining a Balance • Cells must keep the proper concentration of nutrients and water and eliminate wastes. • The plasma membrane is selectively permeable – it will allow some things to pass through, while blocking other things.

9. Diffusion and Osmosis Animations View movement in the cell membrane, diffusion, osmosis Video on Osmosos & Diffusion

10. Structure of the CELL Membrane • Lipid bilayer – two sheets of lipids (phospholipids). • Found around the cell, the nucleus, vacuoles, mitochondria, and chloroplasts. • Embedded with proteins that determine what particles can pass through the membrane.

13. Diffusion • movement of molecules from an area of high concentration to an area of low concentration. • Passive transport / no external energy needed.

14. Diffusion

15. CO2 diffusing into a leaf O2 diffusing out of a leaf O2 diffusing into an animal cell CO2 diffusing out of an animal cell Diffusion in everyday life

16. Name 3 different types of membranes. Explain the term Homeostasis. How does the membranes play a role in maintaining Homeostasis? Explain the role of selectively permeable membranes. Define Diffusion Learning check

17. Osmosis • is the movement of water from a region of high water concentration to a region of low water concentration across a semi-permeable membrane • Passive transport / no external energy needed.

18. osmosis movement of water

20. What is osmosis? • Does osmosis require energy? Learning Check

21. Animal cells in a solution that is the same concentration as their Cytoplasm - stay the same size less concentrated solution - gain water, swell and may burst more concentrated solution - lose water, shrivel and may die Animal cells

22. Osmosis in animal cells

23. Shrivelled Animal Cells

24. What surrounds an animal cell? How does water move in and out of an animal cell? What will happen to animal cells in a very dilute (watery) solution? What will happen to animal cells in a very concentrated solution? Learning check

25. PLANT cells

26. less concentrated solution than their cytoplasm - gain water and become turgid (swells)and strong. Plant cells in a:

27. This turgor pressure gives plants their strength If plants did not have this they would wilt Plants that don’t have wood such as lettuce and house plants rely on turgor pressure for strength Turgor pressure

28. more concentrated solution - lose water and become plasmolysed (wilts). Plant cells in a:

30. What surrounds the membrane of a plant cell? Can this structure control what moves in and out of cells? How does water enter roots of a plant? What is meant by a turgid cell? How could you identify a turgid cell? Learning Check

31. Overcoming Osmosis Amoeba survives in a less concentrated (freshwater) environment due to its contractile vacuole, which eliminates water.

32. Bacteria and Fungi are the most common causes of food spoilage If a food is placed in a high sugary or salty solution then any bacteria or fungi present, will lose the water in their cells by osmosis, shrivel and die. E.g. Salting fish or high sugar concentration in jam. Food Preservation

33. What is meant by plasmolysis? What kind of a solution would you put plant cells in to cause them to palsmolyse? How is plasmolysis used to preserve food? Give an example of some types of food preserved in this way? Learning Check

34. Annimation showing molecules moving in osmosis

35. How Osmosis work – animation + audio lesson Animation: How Osmosis Works Check out this Shockwave video of simple diffusion, facilitated diffusion, and osmosis. This is a great overview of these terms Animation: Membrane

36. Place bags of visking tubing half-filled with (a) distilled water, (b) 80% sucrose solution, in distilled water. Bag (a) stays the same mass and size. Bag (b) increases in mass and swells as water enters due to osmosis. To show osmosis: