The effect of concentration of sucrose solution on the osmosis in potato

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The effect of concentration of sucrose solution on the osmosis in potato

Year 10 Biology IA

0/12/2010

Amanda Hsieh

TABLE OF CONTENTS page number

DESIGN

1.1 Defining the problem 2-3

* Focus / research question

* Hypothesis

* Background information / theory

* Investigation Variables

1.2 Controlling Variables 4

* Treatment of Controlled Variables

* Control Experiment

1.3 Experimental Method 4-5

* Materials

* Risk Assessment

* Method

2 DATA COLLECTION and PROCESSING *

2.1 Recording Raw Data 6-7

* Quantitative Data

* Qualitative Data

2.2 Processing Raw Data 7

* Statistical Processing - calculations

2.3 Presenting Processed Data 7-9

* Result (s) table (s)

* Graph (s)

3 CONCLUSION and EVALUATION *

3.1 Conclusion 9-10

* Conclusion statement

* Conclusion explanation

3.2 Evaluation Procedures 10-11

* Reliability

* Limitations / Weaknesses / errors in Laboratory Investigation

* Significance of weaknesses on experimental results

3.3 Improving the Investigation 11

* Modifications to experiment

BIBLIOGRAPHY

* APPENDIX I: Equipments used in the osmosis experiment 12-13

* APPENDIX II: Diagrams of the osmosis experiment with different 14-15

concentration of sucrose solution

* APPENDIX III: Osmosis Journal 16

* APPENDIC IV: Risk Assesment & Equipment Order Form 17

DESIGN

.1 Defining the problem

Focus / Research question

How does the concentration of sucrose solution affect on the osmosis in potato cells?

Hypothesis

For low concentration of sucrose, the potato will increase in mass. As the concentration of sucrose is increase, the increase of mass will be less. This is because water will move through a semi- permeable cell membrane from a low to a high concentration solution. For higher concentration of sucrose the reverse will occur and the mass of potato will decrease.

Background Information / theory

Diffusion is the random movement of molecules from a region of high concentration to a region of low concentration. Small non-polar molecules such as oxygen and carbon dioxide can cross through a plasma membrane to the region of low concentration. Most of polar molecules can't cross the lipid membrane freely, as they are too big to cross the membrane, like sugars and proteins. Whereas, water molecules are polar, but they can pass through the membrane freely, since they are small enough. This case of diffusion involves the movement of water molecules crossing the membrane called osmosis. (Factors Affecting the Rate of Osmosis, 2010)

"Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration." (How osmosis works, 2010) Semi-permeable membranes are very thin layers of material that selected which molecules can pass through the membrane.

There have three types of solution, isotonic, hypertonic and hypotonic. If the osmotic concentrations of two solutions are equal, the solutions are isotonic. However, when the solutions have unequal osmotic concentrations, the solution with the higher concentration of solutes is hypertonic and the solution with the lower concentration of solutes is hypotonic.

If a potato cell is placed in a hypotonic solution of sucrose, water will defuse in to the potato cell. This will cause the potato cell to increase in size and gain mass. This process will stop when the rigid cell wall will not allow the cell to increase in size any further. The process will also stop if the potato cell became isotonic with the surrounding solution. If a potato cell is placed in a hypertonic solution of sucrose, water will defuse out of the potato cell. This will cause the potato cell to decrease in size and loose mass. This process will continue until either the potato is isotonic with the surrounding solution or else the potato died.
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Investigation variables

(How osmosis works, 2010)

TABLE 1: Practical Investigation Variables

Type of variable

Identified Variable

Independent

Concentration of the sucrose solution in the surrounding solution (0%, 5%, 10%, 15 % and 20%)

Dependent

Mass of 2 cm potato cylinder

Controlled

* size of potato

* size of container

* temperature (room temperature)

* volume of solutions (with difference concentration)

* length of investigation time for each Petri dish

* shape of the potato ( cylinder)

Uncontrolled

...

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