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How does the different concentration of sucrose solution affect the length of the potato strips?

A-Level: Biology

Title:  How does the different concentration of sucrose solution affect the length of the potato strips?
Description  Title: Transport Across Membrane Research Question : How does the different concentration of sucrose solution affect the length of the potato strips? Objective : To investigate the effect of different concentration of sucrose solution on potato strips.
Word Count:  3500


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Hypothesis :
Prediction :
When the potato strips is placed in distilled water or in the lower molarity of sucrose solution, the length of the potato cell increased. The level of the sucrose solution will be decreased. This can be observed by marking the initial level of the sucrose solution before the experiment and after the experiment.
When the potato strips is placed in the higher molarity of sucrose solution, the length of the potato strips will decreased. The level of the sucrose solution will be increased.
When the potato strips is placed in the isotonic solution, there is no change with the length of the potato strips. The level of the sucrose solution also remained the same.
Explanation :
The distilled water and the lower molarity of sucrose solution are hypotonic to the potato cell. Which means, the distilled water and the lower molarity of sucrose solution has higher water concentration and lower solute concentration. Thus, the water molecules diffuse from the sucrose solution into the potato’s cell. As the potato cell gains water, the length of the potato strips increased as the force of water against the plasma membrane caused tugor pressure and maintaining the upright of the cell. The level of sucrose solution decreased as more water molecules are gained by the potato strips.
While the higher molarity of sucrose solution is hypertonic to the potato cell. This means, the higher molarity of the sucrose solution has higher solute concentration and lower water concentration. Thus, the water molecules diffuse out of the cell into the solution. As the potato cell losses water, the vacuole contract and caused the turgor pressure of the cell become less. The length of the potato cell decreased as the plasma the tugor pressure becoming less and the plasma membrane of the potato cell is ‘shrinking’ inwards. The level of the sucrose solution increased as more water molecules diffuse out of the potato cell into the solution.
However, in the isotonic solution, there is no net movement of the water molecules. This will caused no changes in length of the potato strips and the level of sucrose solution.

Variables :
Independent :
The independent variable is plotted on the x-axis and this we choose to manipulate in the experiment. In this experiment the independent variable is :
Concentration of Sucrose
The concentration of sucrose solution used in the experiments is : 0.1M, 0.2M, 0.3M, 0.4M and 0.5M. By adding 10ml of sucrose with 90ml of water would result in 0.1M and so on with 20ml, 30ml, 40ml, and 50ml to be mixed with 80ml, 70ml, 60ml, and 50ml of water accordingly, so that we would have different molarities/concentration of sucrose solution. For the control experiment, we used distilled water. The formulae used to determine the volume of water need to be added to the sucrose solution is :
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