A level Biology Practical Exam Questions and Answers

Explain why the data in the table above are described as processed results. (1) Calculations made from the raw data Describe how you would use a 1.0 mol dm−3 solution of sucrose to produce 30 cm3 of a 0.15 mol dm−3 solution of sucrose (2) *Use ratios 0.15 : 0.85 Add 4.5 cm3 of (1.0 mol dm-3) solution to 25.5 cm3 (distilled) water Describe how you would use the student's results in the table above to find the water potential of the potato tissue. (3) 1. Plot a graph with concentration on the x-axis and percentage change in mass on the y-axis; 2. Find concentration where curve crosses the x-axis / where percentage change is zero; 3. Use (another) resource to find water potential of sucrose concentration (where curve crosses x-axis); Why do you use a cold, isotonic buffer solution? cold to reduce enzyme action isotonic - stops osmosis, maintains the W.P. buffer - prevents damage to enzymes Why is a tissue sample homogenised? (1) To break open the cells