The effects of different concentrations of sucrose on potatoes

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Osmosis Coursework

GCSE Biology Coursework:

The effects of different concentrations of sucrose on potatoes

Planning

Aim:

The aim of this experiment is to investigate if different concentrations of sucrose affect the rate of osmosis in a potato.

Apparatus:

I am going to use

 18 test tubes

 3 test tube racks

 1 potato (large)

 Cylinder cutters

 Weighing scales

 Paper towels

 Stopwatch

 Knife

 Measuring cylinder

 Tweezers

 Cutting tile

Safety

There are a number of safety hazards that can take place during this investigation so these must be addressed. If not, they may cause serious harm.

 Glass breakage, as we are dealing with glass, there is always the danger of dropping a test tube and the glass shattering everywhere. This is why goggles must be worn for one reason to protect the eye from any glass. There is a very high chance of glass slipping out your hand and breaking so goggles are advised.

 Electrical hazards, again as we are working with liquids we must be cautious of any power outlets that may be very near to our workspace. Your chosen workspace must be assessed before any equipment is set up to determine whether there is any danger posed to you in the event of a spillage of liquid.

 Spillages of liquids, spillages of liquids not only present potential electrical hazards they also pose as hazards in themselves. On a slippery surface liquid can cause one to fall and injure themselves severely. In the event of a liquid spillage – all those in close proximity should be warned of the hazard – and the liquid mopped up carefully by you.

 Cutting utensils, knives should be stored away for washing as soon as they are not needed anymore. If a scalpel is kept out for use later on, it should be sheathed with its blade protector so as to avoid any injury.

Prediction:

I predict that the potato in the strong sugar solution will be the smallest in size and have the highest percentage decrease in mass. In addition the potato in the distilled water will be the biggest in size and have the highest percentage increase in mass. Also I predict that the potatoes in the 0.8 and 0.6 molar solutions will decrease in mass and be marginally smaller in size and the 0.4 and 0.2 solutions will have an increase in mass and be marginally bigger in size. 

I also predict that the potatoes in the solutions with more water will become bigger and heavier, as water will diffuse in. This is according to the law of osmosis, which is the fact that water molecules from a region of high concentration move to a region of low concentration; taking place through a partially permeable membrane. In addition, I predict that the potato in the 0 molar sugar solution will be bigger in size and heavier in mass than the 0.2 and 0.4 molar sugar solutions.

As I know due to background knowledge, the cell membrane will not allow larger molecules such as Sucrose, Starch, protein, etc. to pass through, as the membrane is partially permeable. This fact supports my prediction and assists the way in which I thought about it.

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I expect my hypothesis to be correct as it is accorded to my background information. Osmosis is defined as the net movement of water or any other solution is molecules from a region in which they are highly concentrated to a region in which they are less concentrated. This movement must take place across a partially permeable membrane such as a cell wall, which lets smaller molecules such as water through but does not allow bigger molecules to pass through. The molecules will continue to diffuse until the area in which the molecules are found reaches a state of equilibrium, ...

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