Osmosis Internal Assessment - Biology Higher Level

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The effect of salinity on osmosis of solanum tuberosum L.(potatoes)| Biology HL Internal Assessment – Year 10|
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Teresa Nguyen|
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Table of Contents
1 DESIGN2
1.1 Defining the problem2
FOCUS QUESTION2
HYPOTHESIS2
BACKGROUND INFORMATION2
INVESTIGATION VARIABLES3
1.2 Controlling Variables3
TREATMENT OF THE CONTROLLED VARIABLES3
CONTROL EXPERIMENT4
1.3 Experimental Method4
MATERIALS4
RISK ASSESSMENT5
METHOD5
2 DATA COLLECTION and PROCESSING7
2.1 Recording Raw data7
QUANTITATIVE RAW DATA7
QUALITATIVE RAW DATA7
2.2 Processing Raw Data8
Processed Data Table9
3 Conclusions and Evaluation11
3.1 Conclusion11
CONCLUSION STATEMENT11
CONCLUSION EXPLANATION11
3.2 Evaluation Procedures12
RELIABLITY12
LIMITATIONS/WEAKNESSES/ERROR IN LABORATORY INVESTIGATIONS13
3.3 Improving the Investigation14
MODIFICATION TO THE EXPERIMENT14
Bibliography15
Appendixes16
Appendix A – Risk Assessment16
Appendix B – Turnitin Receipt19
Appendix C – Journal19

1 DESIGN
1.1 Defining the problem
FOCUS QUESTION
What is the effect of osmosis on the mass (g) of solanum tuberosum L. (potatoes) after duration of 24 hours in varying concentration levels (2%, 5%, 10%, 20% and 25%) of sodium chloride (table salt)?

HYPOTHESIS
Solanum tuberosum L. final masses will decline as the concentration (2%, 5%, 10%, 20% and 25%) of sodium chloride increases. Potato slices placed in distilled water will have higher mass percentage due to the cells becoming turgid.

BACKGROUND INFORMATION
Diffusion is the movement of molecules from a hypertonic (high concentration solute) to the hypotonic (low concentration of solute). There are different types of diffusion one of which is osmosis. Osmosis is the movement of water molecules through a semipermeable membrane that allows only smaller molecules such as water to pass through and prevent larger molecules to enter such as glucose or sodium chloride. (Bozeman Biology, 2012)

Within osmosis comparison between the different solutions standard terminology are used to describe the differences such as Isotonic, hypertonic and hypotonic as mentioned earlier. Isotonic is when the solution has equal concentration of solutes. Hypertonic is when the solution has concentration of the solute. In contrast, hypotonic is when the solution has lower concentration of the solute. (Bowen, 2002)

Plant cells are known to have strong cell walls that when osmosis allows water to be taken up it swells. However, to prevent the cell from bursting the cells become turgid. The pressure within the cell rises and gradually the internal pressure has increased to an extent which even water molecules cannot enter. (Nigel D Purchon, 2012) This is convenient for plants as they do not have skeletons, thus their leaves and stems are supported by the pressure of the water. Loss of water by osmosis causes the plant to become flaccid which the plasma membrane withers from the cell wall. (BBC, 2012) INVESTIGATION VARIABLES

TABLE 1 – Practical Investigation Variables
Type of Variable| Identified Variable |
Independent | The varied concentration level of Sodium Chloride (2%, 5%, 10%, 20% and 25%).| Dependent | The differentiation of masses of the different potato pieces (final – initial mass) in each Sodium Chloride concentrations (2%, 5%, 10%, 20% and 25%) after 24 hours.| Controlled| Each trial is from the same potato. The quantity of solution given in each trial. The size of potato slices.Source of biological material. Potato pieces in distilled water. The duration of the investigation. The size of the test tubes. | Uncontrolled | Rate of osmosis.The initial salt concentration in the potato. Change in room temperature.| 1.2 Controlling Variables

TREATMENT OF THE CONTROLLED VARIABLES
TABLE 2: Control Treatment of Variable
Control Variables | Treatment |
Each trial is from the same potato. | Each trial used...
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