Osmosis & diffusion. IGCSE

1. How substances get in and out of cells Mainly based on the exercises from http://www.biology-resources.com/biology-questions.html IGCSE Revision Questions http://biodeluna.wordpress.com

5. Which of the statements is an acceptable description of diffusion ? (i) The movement of water from a concentrated solution to a dilute solution across a partially permeable membrane. . (ii) The movement of a dissolved substance from a concentrated solution to a dilute solution across a partially permeable membrane. (iii) The movement of water from a dilute solution to a concentrated solution across a partially permeable membrane. (iv) The uptake of water by a living cell.

6. Which of the statements is an acceptable description of diffusion ? (i) The movement of water from a concentrated solution to a dilute solution across a partially permeable membrane. . (ii) The movement of a dissolved substance from a concentrated solution to a dilute solution across a partially permeable membrane. (iii) The movement of water from a dilute solution to a concentrated solution across a partially permeable membrane. (iv) The uptake of water by a living cell.

7. Definition of osmosis

9. Description of diffusion

11. Active transport

17. (a) a lower osmotic potential (water potential) than its own cytoplasm Plasmolysis (b) a higher osmotic potential (water potential) than its own cytoplasm.

19. When meat is salted, bacteria cannot grow on it. Suggest a reason for this.

20. When a cell is respiring aerobically, which two gases are likely to be diffusing in and out of the cell, and in which direction will they be diffusing?

24. water and iodine starch and glucose solutions A piece of dialysis (‘Visking’) tubing is knotted at one end water and iodine and filled with a 2 % starch solution mixed with a 10% glucose solution. The tube is immersed in.a test-tube of water to which iodine has been added. (a ) Predict what you will see after 30 minutes (i) in the starch and glucose solutions dialysis tube, (ii) in the test-tube, (iii) when you boil the liquid from the test-tube with Benedict's solution. (b) Give an explanation of these results.