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osmosis coursework

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Introduction

Osmosis coursework Biology Katie Smith Aim: Our aim is to investigate whether the mass of a potato chip changes when put in different concentrations of sucrose solution. Planning: Osmosis is a type of diffusion. Its diffusion of water from a dilute solution to a more concentrated solution through a semi permeable membrane which only allows water molecules to pass but not solute molecules. Water can pass in due to osmosis when a cell is in a less concentrated solution. When osmosis occurs water flows through the cell wall and cell membrane into the cytoplasm and vacuole. When no more water can be entered we say the cell is fully turgid in other words swollen. However water can also pass out of the cytoplasm through the cell membrane and cell wall into the solutions outside the cell, and this can happen if a cell is in a more concentrated solution. When this happens we say the cell has become flaccid in other words flaccid. When a protoplasm in a plant cell shrinks due to loss of water through osmosis, and also makes the plant cell flaccid and this process is also called plamolysis. Osmotic potential is when you measure the reduction in a solution when it has a dissolved solute or dissolved solutions. We can also say that if a plant cell is put into pre water it would gain mass because the water would be moving from a higher concentration to a lower concentration. ...read more.

Middle

I am choosing this range because my results show that between 0-20% of sucrose solution mass is gained and also lost . After finishing my preliminary work I have chosen a range of the concentrations of sucrose solution which I will be using for my actual experiment. The concentrations of sucrose solution I will be using for my actual experiment are 8%, 10%, 12%, 14% and 16%. Prediction: I predict that when I will be using the following concentrations of sucrose solution 8%, 10%, 12%, 14% and 16% the mass of the potato chip will decrease as the concentration of the sucrose solution will increase. I can predict this from the results I got in my preliminary work. The potato would loose weight in a strong sugar solution and it would gain weight in pure water. Osmosis happens when water moves from a high concentration to a low concentration, so when a potato chip would be put in pure water it would gain weight because the water would be moving from a high concentration (pure water) to a low concentration (potato chip). However if a potato chip would be put into a strong sugar solution it would loose mass because the water would be moving from a high concentration (potato chip) to a low concentration (strong sugar solution). I also predict that the concentration of sucrose solution at 8% and 10% the potato chip will gain mass and the rest, 12%, 14% and 16% of sucrose solution will make the potato chip loose weight. ...read more.

Conclusion

I started off straight away and followed the method I wrote down, by following the easy steps of my method I had the whole experiment ready to go in just a little time. I repeated the experiment two times to make sure that the results I would obtain at the end would be reliable. To make sure I had the right amount of everything I used a lot of equipment for example the graduating pipette, a ruler and a weighing machine. I measured and double checked everything and then proceeded with the experiment. Although I carried out my experiment very thoroughly I still received an anomalous result. At the 14% sucrose solution I put in two potato chips in the same concentration, however when I was collecting my results I noticed that although the mass of both potato chips were same at the beginning (2.2g) one of them had lost 0.2g and the other had lost 0.1g. This meant that something had gone wrong, maybe the temperature, the amount of time or the mass. So it was not a fair test as one result came out a bit wrong. Next time to improve my coursework I will make sure I take all readings more accurately and also make sure that next time I will put all test tubes in an area where I'm sure the temperature will stay the same. ?? ?? ?? ?? ...read more.

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