CHAPTER 3 Movement of Substances

1. CHAPTER 3 Movement of Substances

2. Chapter 3 Movement of Substances 3.1 Diffusion 3.2 Osmosis 3.3 Surface Area to Volume Ratio 3.4 Active Transport

3. 3.1 Diffusion • Learning Outcomes • After this section, you should be able to: • define diffusion; and • discuss the importance of diffusion in nutrient uptake and gaseous exchange in plants and humans.

4. 3.1 Diffusion How do particles move? Think of a time when you detected the smell of perfume in a room. How has the smell travelled to your nose? Region B with lower concentration of particles Region A with higher concentration of particles Movement of particles

5. 3.1 Diffusion What is diffusion? Diffusion is the net movement of particles from a region where they are of higher concentrationto a region where they are of lower concentration, that is, down a concentration gradient.

6. 3.1 Diffusion Concentration gradient Concentration gradient is the difference in concentrations between two regions. direction of movement of particles molecules diffuse down a concentration gradient Concentration Distance Point A Point B

7. 3.1 Diffusion How is a concentration gradient related to diffusion? • The movement of fluid particles is diffusion . • Particles will diffuse downtheir concentration gradient. • The steeperthe concentration gradient, the higherthe rate of diffusion. URL

8. 3.1 Diffusion Diffusion of a dissolved substance • A copper sulfate crystal is dropped into a gas jar containing water. • The gas jar is allowed to stand for a few days. • The blue colour gradually spreads throughout the water. • The copper sulfate particles diffuse evenly throughout the water. gas jar water copper sulfate crystal

9. 3.1 Diffusion Diffusion across a membrane • Both the ___________ and ___________ are able to pass through a _________________________. permeable membrane potassium iodide particle Copper sulfate and potassium iodide particles evenly distributed copper sulfate particle

10. 3.1 Diffusion Diffusion of gases in the lungs ______________________in the lungs occurs via diffusion. air space in the lungs CO2 diffuses from blood into the lungs O2 diffuses from lungs into the blood red blood cell lung cell

11. Chapter 3 Movement of Substances 3.1 Diffusion 3.2 Osmosis 3.3 Surface Area to Volume Ratio 3.4 Active Transport

12. 3.2 Osmosis • Learning Outcomes • After this section, you should be able to: • define osmosis; and • discuss the effects of osmosis on plant and animal tissues.

13. 3.2 Osmosis What is osmosis? • A _______________________________allows some substances to pass through it but not others. A B 5% sucrose solution (more water, less sucrose) 10% sucrose solution (less water, more sucrose) sucrose molecule water molecule partially permeable membrane

14. 3.2 Osmosis What is osmosis? • The partially permeable membrane allows water molecules to pass through but not sucrose molecules. A B rise in level of solution drop in level due to movement of water molecules to A partially permeable membrane

15. 3.2 Osmosis How can we demonstrate osmosis? An experiment is set up as shown. The level of the solution in the thistle funnel is observed to rise. This is due to water molecules moving into the thistle funnel from the beaker. thistlefunnel retortstand sucrose solution cellophane paper beaker water

16. 3.2 Osmosis What is water potential and how is it related to osmosis? • The ____________________________________ is known as water potential. • A dilute solution has a higher water potential. • Aconcentratedsolution has a lower water potential.

17. 3.2 Osmosis What is water potential and how is it related to osmosis? A _____________________________ is established when a partially permeable membrane separates two solutions of different water potentials. partially permeable membrane more solute, lower water potential less solute, higher water potential water potential gradient established water moves down the gradient

18. 3.2 Osmosis What is water potential and how is it related to osmosis? _____________is the net _________________ _____________from a solution of higher water potential to a solution of lower water potential, through a ______________________________. URL

19. 3.2 Osmosis How does osmosis affect living organisms? Cells are living ________________________. Plant cell Animal cell partially permeable cell surface membrane fully permeable cellulose cell wall enclosed nucleus and cytoplasm containing various dissolved substances

20. 3.2 Osmosis 4 What happens to a cell in a solution with higher water potential? 1 3 2 cell sap has lower water potential than surrounding solution water enters by osmosis cell sap in vacuole in solution of higher water potential cell expands and becomes __________ plant cell cell wall prevents cell from bursting

21. 3.2 Osmosis What happens to a cell in a solution with higher water potential? cytoplasm has lower water potential than outside solution, water enters by osmosis in solution of higher water potential animal cell cell expands and _________

22. 3.2 Osmosis What happens to a cell in a solution with lower water potential? 1 3 4 2 cell sap has higher water potential than surrounding solution cell sap in vacuole water leaves by osmosis in solution with low water potential plant cell cytoplasm shrinks away from cell wall and cell becomes _____________ cell becomes ___________

23. 3.2 Osmosis What happens to a cell in a solution with lower water potential? cytoplasm has higher water potential than surrounding solution, water leaves by osmosis in solution of lower water potential animal cell cell shrinks in sizeand becomes _____________ URL

24. 3.2 Osmosis What happens to a cell in a solution of the same water potential? A cell immersed in a solution with the same water potential as its cytoplasm _____________________ ____________________.

25. 3.2 Osmosis Why is turgor important in plants? • Turgor plays an important role in _____________ _____________________ in plants. • It keeps herbaceous (non-woody) plants________________________________. • Loss of turgidity causes the plant to __________.

26. 3.2 Osmosis Why is turgor important in plants? • Changes in turgor also cause the movements of some plant parts, e.g. opening and closing of stomata. turgor in guard cells causes stoma to open in the day lack of turgor in guard cells causes stoma to close at night

27. 3.2 Osmosis Why is turgor important in plants? • Plasmolysis causes tissues to become limp or ________________. • When cells of a plant become flaccid, the plant _____________. • Water may be added to the soil to dilute the soil solution. This causes water moelcules to enter the plant cells and keeps the plant firm and upright.

28. Chapter 3 Movement of Substances 3.1 Diffusion 3.2 Osmosis 3.3 Surface Area to Volume Ratio 3.4 Active Transport

29. 3.3 Surface Area to Volume Ratio • Learning Outcomes • After this section, you should be able to: • explain how surface area to volume ratio affects the rate of movement of substances.

30. 3.3 Surface Area to Volume Ratio What does surface area to volume ratio mean to a cell? The ___________the surface area to volume ratio, the _____________ the rate of _____________.

31. Cube Surface area/cm2 Volume/cm3 Surface area: volume Cell A1(side 1 cm) Cell A2 (side 2 cm) Cell A3(side 3 cm) 3.3 Surface Area to Volume Ratio What does surface area to volume ratio mean to a cell? 6 1 _________ 24 8 _________ 54 27 _________ As a cell becomes bigger, its surface area to volume ratio decreases.

32. 3.3 Surface Area to Volume Ratio food + O2 in Each shaded square represents a unit volume of protoplasm waste products out Cell A3 Cell A2 Cell A1 Y Z X loss in surface area loss in surface area

33. 3.3 Surface Area to Volume Ratio How are cells adapted for the absorption of materials? • Cells which function in absorption have an ____________________________________. • For example, root cells have long processes and epithelial cells have a folded cell membrane. Epithelial cell Root hair cell

34. Chapter 3 Movement of Substances 3.1 Diffusion 3.2 Osmosis 3.3 Surface Area to Volume Ratio 3.4 Active Transport

35. 3.4 Active Transport • Learning Outcomes • After this section, you should be able to: • define active transport; • explain that active transport is an energy-consuming process by which substances are transported against a concentration gradient; and

36. 3.4 Active Transport What is active transport? • ______________________is the process in which energy is used to move the particles of a substance across a membrane _________ • _________________, that is, from a region • where the particles are of lower concentration to • a region where they are of higher concentration.

37. 3.4 Active Transport ______________ down a concentration gradient _______________ against a concentration gradient requires ___________ higher concentration of solute molecules, e.g. glucose. lower concentration of solute molecules, e.g. glucose.

38. 3.4 Active Transport • Since active transport requires energy, active transport occurs only in ___________________. • Dissolved mineral salts are taken up by root hair cells via active transport. root hair cell mineral salts path taken by substances absorbed by root hair cell soil solution

39. Chapter 3 Movement of Substances

40. Chapter 3 Movement of Substances The URLs are valid as at 15 January 2014.