Planning an experiment (Example: describe an experiment to determine the water potential of potato tissue)
by LUM WAI MEI
1. 4. Dependent variable (Record results in table)
1.1. Measure the final length of each potato piece and calculate the change in length
1.2. change in length to be recorded as +5 mm or -5 mm
1.3. Increase reliability of experiment: 2 measurements for each concentration to be taken and calculate the average change in length
2. 5. Construct a graph (dependent variable at y-axis, independent variable at x-axis)
2.1. graph of fruit juice concentration against the change in length of the potato tissue
3. 6. Conclusion
3.1. Read from the graph the value of the concentration of fruit juice at the point where the graph crossed the x-axis. That was the water potential of the potato tissue.
4. 3. Controlled variables
4.1. potato pieces must be of equal dimensions - 60 mm x 10 mm x 3 mm
4.2. potato pieces placed in different solutions for the same duration of time (20 minutes)
5. 2. Basic procedures
5.1. pieces of potato tissue were cut and placed in different solutions for 20 minutes
5.2. After 20 minutes, remove the potato pieces from the solutions and dry carefully with paper towel.
6. 1. Independent variable (State 5 different concentrations of fruit juices)
6.1. 0.0 mol per dm^3, 0.2 mol per dm^3, 0.4 mol per dm^3, 0.6 mol per dm^3, 0.8 mol per dm^3
