1. Cells revision – Past papers

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3. Why do we use stains when Looking at cells under the microscope? 2

4. Diffusion and osmosis here 3

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6. Why is diffusion important to all organisms? Amoeba Unicellular organisms Multicellular organisms Bacteria 5

7. Cell division 6

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9. -What is characteristic of daughter cells? -What is the chromosome complement? - what happens if a daughter cell does not inherit exactly the same number of chromosomoses as the original cell? 8

10. Enzymes: -what do you remember about them - which substrate/ product and enzyme do you remember? 9

11. Problem solving with enzymes Optimum conditions and working range 10

12. Problem solving with enzymes Fair experiment - When doing experiments in order to test the activity of enzymes, which variables should be carefully controlled? - Mass of sample, volume of sample (NOT SIZE, it is too vague), surface area of the sample, temperature, pH, volumes of solutions, size of equipment, origin of biological material. Watch! Never use a variable which is obviously shown in the diagram or mentioned in details in the question 11

13. State two factors that should stay the same and why 12

14. -What is the name given to tube B? - What is the purpose of setting tube B? 14

15. Problem solving with enzymes Controls - What is a control and how is it set-up? A control is a repeat of an experiment designed to show that the factor being tested is actually responsible for the effect observed in the original experiment. For the control, you need to: - use a material in which biological activity has been destroyed by boiling, cooking, or sterilizing. - use an equivalent mass or volume of glass beads or anything which has not got biological activity 13

16. -What do living cells need energy for? - what do you know about aerobic respiration? -herehere 15