2005 BIOLOGY PAPER 3-QUESTION 2

The mass and freshness of plant tissues are influenced by osmosis. Osmosis is influenced by the concentration of soluble substances inside and outside the cells.
Situation:
A farmer has a rambutan orchard. Since the product of his orchard is abundant, he decided to produce rambutan jam. Before the rambutan fruits are processed into jam, the mass has to be maintained temporarily. Therefore, the farmer has to determine the solution and the concentration of the solution that should be used.
Based on the above information and situation, design a laboratory experiment to determine the concentration of the solution which will maintain the mass of plant tissues.
Use a suitable plant tissue when designing your experiment.
The planning of your experiment must include the following aspects:
• Statement of identified problem
• Objective of study
• Variables
• Statement of hypothesis
• List of materials and apparatus
• Technique used
• Experimental procedure
• Presentation of data
• Conclusion

ANSWER

1. Objective of study:
To determine the concentration of sucrose solution that will maintain the mass of plant tissues.

2. Statement of identified problem:
What is the concentration of sucrose solution that will maintain the mass of potato tissues?

3. Statement of hypotesis:
As the concentration of the sucrose solution increases, the mass of potato tissues decreases. The concentration of the sucrose that did not cause any change in mass of the potato will maintain the mass of the potato.

4. Variables:
i. Manipulated - concentration of sucrose solution
ii. Responding - change in mass of potato tissues
iii. Controlled – Type of potato, volume of solution, soaking time

5. List of materials and apparatus:
Materials: Potatoes, sucrose solution, filter paper
Apparatus: Cork borer/knife, test tube/beaker, balance/weighing machine

6. Technique:
Calculate the change in mass of potato tissues in different concentrations of sucrose solution using formula: Final mass – Initial mass (g)

7. Method:
i. Cut out a potato to get potato strips of the same size and weigh them.
ii. Fill 3 separate beakers with sucrose solutions of 0.5%, 5% and 20%
iii. Put 5 potato strips of the same size in each beaker
iv. Leave the potato strips immersed in the sucrose solution for 1 hour
v. After 1 hour, take out the potato strips from each beaker, dry them using filter paper.
vi. Weigh the potato strips taken out from each beaker.
vii. Record the mass of the potato strips in a result table.
viii. Plot a graph of the concentration of sucrose solution against mass of potato strips.
Precautions:
1. Dry the potato strips thoroughly with filter paper.
2. Use more than 5 strips and find the average mass of potato strips.

8. Data presentation

Concentration of sucrose solution/%	0.5	5	20
Initial mass of potato strips/g	Table Cell	Table Cell	Table Cell
Final mass of potato strips/g	Table Cell	Table Cell	Table Cell
Change in mass of potato strips/g	Table Cell	Table Cell	Table Cell

9. Conclusion
As the concentration of the sucrose solution increases, the mass of the potato tissue decreases. The concentration of the sucrose that did not cause any change in mass of the potato will maintain the mass of the potato. Hypothesis is accepted.