Cell Membrane Lab Report

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Cells are the basis of all life forms. Cells are separated from each other and the surrounding environments by the cell membrane (and cell wall in plants). The cell membrane keeps together the cell’s organelles (the nucleus and mitochondria for example) by forming a semi-permeable barrier, allowing specific molecules to enter and leave the cell. This movement of substances entering and leaving the cell is called active transport (when the movement uses energy) or passive transport (when the movement uses no energy).
Passive transport is the diffusion of a substance across a membrane with no energy investment.
Diffusion is the movement of molecules of any substance so that they spread out evenly in the available space.
The diffusion
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The 1.0M Sucrose solution height increased more rapidly, at a rate of 4.3mm per minute to reach a maximum height of 195mm at 45 minutes.
The 1.0M Sodium Chloride solution height increased rapidly, then plateaued around the 30 minute mark at a rate of 2mm per minute to reach a maximum of 90mm at 45 minutes.
As discussed in the introduction, the movement of water across the cell membrane depends upon the concentration of solutes on both sides of the cell membrane. The cell membrane in this experiment, was the semi-permeable dialysis bag. A substance will diffuse down it concentration gradient, from where it is more concentrated, to where it is less. A cell immersed in plain water tends to swell as water diffuses in from the hypotonic solution. This result was shown in this experiment with both sucrose solutions, where the water diffused into the dialysis bag, and pushed the solution up into the straw. The higher the amount of sucrose causes more water to move into the dialysis
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Passive transport (osmosis and diffusion) using a non-living object was observed and different rates of movement using three different solution of varying concentrations was also observed and recorded. It was an interesting and and useful opportunity to learn about osmosis and diffusion in the cell.
Reference List
1. Reece J.B., Myers N., Urry L.A., Cain M.L, Wasserman S.A., Minorsky P.V., Jackson R.B., Cooke B.N. (2012). Campbell Biology. 10th edn., Australian version, Pearson Publishing Australia
2. Kennedy U. and Dearnaley J.D.W. (2016). Biology 1. Practical Notes and Exercises. University of Southern Queensland, Toowoomba.
3. Source: Boundless. “Introduction to Osmoregulation.” Boundless Biology. Boundless, 13 Apr. 2016. Retrieved 14 Apr. 2016 from https://www.boundless.com/biology/textbooks/boundless-biology-textbook/osmotic-regulation-and-the-excretory-system-41/osmoregulation-and-osmotic-balance-228/introduction-to-osmoregulation-856-12102/
4. Friedrichsen, P.M. & Pallant, A. 2007, "French Fries, Dialysis Tubing & Computer Models: Teaching Diffusion & Osmosis Through Inquiry & Modeling", The American Biology Teacher, vol. 69, no. 2, pp.

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