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Osmosis Internal Assessment (Biology)

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Introduction

BIOLOGY INTERNAL ASSESSMENT STANDARD LEVEL OSMOSIS OSMOSIS IN POTATO STRIPS i. Aim To investigate the change in the mass of potato strips as a result of the process of osmosis in potato strips over varying periods of time. ii. Research Question How does time affect the mass of potato strips (measured in grams) when immersed in distilled water (H20) over a period of five hours at one hour intervals: 1 hour, 2 hours, 3 hours, 4 hours, and 5 hours? iii. Introduction Osmosis is the passive movement of water molecules from a region of high water concentration to a region of lower water concentration (lower solute concentration to higher solute concentration), across a partially permeable membrane.1 The plasma membrane is selectively permeable, and it controls the movement of substances in and out of cells, but water is able to move freely in and out of the cell, allowing osmosis to occur.2 Potato cells have selectively permeable membranes and therefore can be used to show the process of osmosis. As plant cells generally have a higher solute concentration than their surroundings (lower water concentration), when immersed in H20, the potato strips will be surrounded by a region of high water concentration since water has a solute concentration of 0.3 This would mean that the distilled water is hypotonic whereby it has a higher concentration of water than the potato cells, causing water to flow from the area of higher water concentration (water solution) ...read more.

Middle

Dispose of all used material appropriately. vii. Results Table 1. Initial and final mass of the potato strips after immersion in distilled water () over a period of five hours at one hour intervals Duration given for osmosis to occur (hours ? 1min) Initial and final mass of potato strips ?0.1g Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Initial Mass Final Mass Initial Mass Final Mass Initial Mass Final Mass Initial Mass Final Mass Initial Mass Final Mass 1.0 3.0 3.0 3.0 3.0 3.0 3.1 3.0 3.2 3.0 3.0 2.0 3.0 3.2 3.0 3.3 3.0 3.3 3.0 3.2 3.0 3.1 3.0 3.0 3.4 3.0 3.4 3.0 3.6 3.0 3.5 3.0 3.4 4.0 3.0 3.5 3.0 3.6 3.0 3.5 3.0 3.7 3.0 3.7 5.0 3.0 3.6 3.0 3.6 3.0 3.6 3.0 3.7 3.0 3.6 *Note that the initial mass of all the potato strips are the same Table 2. Mean, standard deviation, and 33.33% of the mean for the final mass of potato strips immersed in distilled water () Duration given for osmosis to occur (hours ? 1min) Mean, S.D, and 33.33% of mean of final mass of potato strips ?0.1g Mean S.D. 33.33% of mean 1.0 3.1 0.09 1.02 2.0 3.3 0.08 1.09 3.0 3.5 0.09 1.16 4.0 3.6 0.10 1.19 5.0 3.6 0.04 1.19 *As the Standard Deviation is less than 33.33% of the mean for all the values of final mass of the potato strips, it can be seen that these mean values are accurate. ...read more.

Conclusion

Way in which mass was measured The mass of the potato strips were recorded using an electronic weighing scale up to only one decimal place, thus resulting in minimal differences in data collection, making conclusions more general and vague. Using a weighing scale with up to two decimal places will allow the data collected to be more accurate. Frequency of data collection* The mass of the potato strips were recorded after immersion in distilled water for 1 hour, 2 hours, 3 hours, 4 hours, and 5 hours, meaning large gaps between the data points, causing conclusions to be less accurate as the data was less reliable, and trends were more general and rather vague. Collection of data should occur at half an hour intervals over a period of six hours, providing ample data to make detailed conclusions. 1 Andrew Allot. IB Study Guide: Biology Standard and Higher Level (2nd edition). UK: Oxford University Press, 2007. 2 Alberts B, Johnson A, Lewis J. Molecular Biology of the Cell (4th edition). New York: Garland Science, 2002. 3 M B V Roberts. Biology, A functional approach (4th edition). UK: Thomson Nelson and Sons Ltd, 1986. 4 Ibid. 5 Regina Bailey. "Diffusion and Passive Transport" About.com Guide. Biology. 11 May 2011. <http://biology.about.com/od/cellularprocesses/ss/diffusion_3.htm>. 6 Alberts B, Johnson A, Lewis J. Molecular Biology of the Cell (4th edition). New York: Garland Science, 2002. ?? ?? ?? ?? Biology Internal Assessment - Osmosis Page 1 of 11 ...read more.

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Here's what a teacher thought of this essay

4 star(s)

****
An excellent investigation into the effect of osmosis on the potato chips.
The introduction gave a good scientific foundation for the investigation and was well laid out with relevant information.
The method was very thorough and gave enough detail for the investigation to be repeated.
One limitation to the experiment was the independent variable. By choosing time it left the scientific analysis a little basic as osmosis continuing to happen over time is rather obvious.
The analysis of the data was excellent. The graphs clearly shown the general trend of the results.

Marked by teacher Jon Borrell 22/05/2013

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