Movement of Substances (part 2): Active transport & comparisons between diffusion, osmosis and active transport

1. 3) Active transport

2. Active transport Definition: The process in which energy is used to move the particles of a substance against a concentration gradient from a region where they are in lower concentration to a region where they are in higher concentration.

3. Active transport ⚫ Occurs only in living things (because living things respire to obtain energy required in active transport) ⚫ Involved in the absorption of a) dissolved mineral salts by the root hairs b) glucose and amino acids by cells in the small intestine of humans

4. Energy High concentration Low concentration

6. Summary Chapter 3

7. partially permeable ⚫

8. Summary

9. Differences between Diffusion, Osmosis and Active transport Process Movement of Molecules/ ions Condition Additional requirements Down a conc. gradient Diffusion High conc. to low conc. Osmosis Water molecules High water potential to low water potential Low conc. to high conc. Across a partially permeable membrane Active transport Particles of substances Against a conc. Gradient; Energy required

10. Differences between Osmosis and Diffusion Osmosis 1.It involves flow of solvent molecules in one direction. 2.It requires partially permeable membrane. 3.It is a slow process . 4.Occurs only in liquids. 5.The movement is over a short distance Diffusion 1.Flow of either solute or solvent molecules is in both directions. 2.No such membrane is required. 3.It is a fast process. 4.Occurs in liquids as well as gases 5.Movements are over large distances

11. Temperature & diffusion ⚫ The higher the temperature of the solution, the faster the rate of diffusion

12. Molecular Wt. and Diffusion ⚫ The higher the molecular weight of the molecule, the slower the rate of diffusion