14/05/2022
SPM Biology practical session
Title: Determining the concentration of an external solution which is isotonic to the cell sap of a plant
Aim: To determine the concentration of an external solution which is isotonic to the cell sap of a plant
Problem Statement: What is the concentration of an external (sucrose) solution which is isotonic to the cell sap of plants?
Hypothesis: The concentration of the solution which is isotonic to the cell sap of plant cells has no effect on the mass, length and size of plant cells.
Variables:
Manipulated variable: Concentration of sucrose solution
Responding variable: Length of potato strips / Mass of potato strips
Fixed variable: Volume of sucrose solution used, surrounding temperature and time
Materials:
Fresh potato
Distilled water, sucrose solution (3tsp, 5tsp, 7tsp, 9tsp)
Apparatus:
Knife, 200mL container, ruler, skin peeler, teaspoon, stopwatch.
Procedure:
1. Five containers were labelled as A, B, C, D and E.
2. Each container was filled with distilled water and sucrose solution of 1tsp, 3tsp, 5tsp, 7tsp and 9tsp sugar respectively.
3. 15 rectangular potato strips with dimension of 1cm*0.5cm*5cm were cut using knife.
4. The potato strips were measured to ensure the length of 5cm for every strip.
5. 3 potato strips were immersed into each container and left for 30 min.
6. Each potato strip was dried with tissue paper and the final length of each potato strips was recorded.
