Biology 9700/53 May June 2011 | Cambridge AS Level Past Papers With Mark Scheme

1. Water potential of plant tissue investigated by observing sucrose solution density changes after osmosis; droplet movement in sucrose gradients used for estimation.

2. Control variables for osmosis experiments: sucrose solution concentration, volume, and tissue integrity; potential effects of uncontrolled variables on rate of droplet movement.

3. Microscopic appearance of plant cells in hypotonic (turgid cells) vs. hypertonic (plasmolysed cells) sucrose solutions, with diagrams emphasizing structural changes.

4. FF-MAS effects on oocyte meiosis stimulation in mice tested against cholesterol and activator compounds at varying concentrations, statistical significance analyzed via SM values.

5. Null hypothesis for meiosis activation: no difference between FF-MAS and other compounds; statistical validation using t-tests for comparing group means.

6. Experimental findings: FF-MAS showed significantly higher meiosis stimulation compared to other compounds, supporting its role in activating membrane receptor LXR alpha.