Experiment To Investigate the Plasmolysis Rate and Concentration of Sucrose Solution In the Onion Cell

The cells will be plasmolysed more as the concentration increases. And incipient plasmolysis is the point when 50% of the cells are plasmolysed.

Around 0.35M point, the rate of plasmolysis is the greatest.

Apparatus

Onion bulb

6 petri dishes

6 test tubes

test tube rack

wax pencil

six 10cm graduated pipettes

six beakers

fine brush

distilled water

M sucrose solution

fine forceps

paster pipettes

slide and cover slips

microscope

graph paper

lazor blade

tile

procedure

label six

% of plasmolysed cells in the onion

concentration of sucrose solution

st

2nd

3rd

average

0.2M

0.0

3.6

.7

.77

0.3M

5.8

22.0

22.1

9.97

0.35M

46.8

56.3

38.5

47.18

0.4M

69.3

54.5

57.3

60.40

0.5M

94.6

91.2

89.2

91.70

.0M

98.7

95.1

96.0

96.67

Table of the percentage of the plasmolysed cells in the onion and the concentration of sucrose solution used

Limitation factors

. The standard of plasmolysed cell was too vague. In truth, we cannot exactly judge whether the cell is plasmolysed or not.

2. The used part of onion cell is not even and identical. The concentration of cell sap is different from place to place so that the degree of plasmolysis can be different.

3. The time may affect the result. Although the osmosis will stop when it reaches the equilibrium, we do not know when the equilibrium point is. Therefore, we might take the onion piece out too earlier so that the plasmolysis would not be fully accomplished.

4. the other component within the cell sap may give the unwanted error.

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