- I will make sure my working area is clear of bags or any obstacles.
- I will make sure everyone in my group will were safety goggles to prevent water or glucose going in the eye.
- I will always look at the knife while it is in use or not in use so you don’t cut yourself or hurt anyone else.
- I will give the knife back to my teacher when we have finished our experiment to prevent injury.
- I will make sure no water is spilt on the floor, if the is water spilt I will clean it up as some one not looking could slip and hurt themselves.
P4a variables and fair testing
- The variables that can effect my investigation is the strength of my solution, the size of the potato chip, the volume of the liquid, the temperature (it can effect it as it can evaporate the liquid), the amount of time the potato chips remain in the solution, all these variables can effect my investigation.
- The variable I am going to look at is the strength of the solution. To make this investigation a fair test I am going to vary the strength of the solution but I will keep the other entire variable the same. I will cut each potato chip so they are the same size so osmosis does not occur more in an other tube. The volume of solution in each test tube will be the same. I will make sure my hands are clean and dry so it does not effect my investigation.
- When I remove the chips from the solution I will gently dry them with a paper towel so osmosis does not occur outside the experimental conditions. All the potato chips will be in the solution for the same amount of time.
P4b List of equipment
Potato chipper Knife Tubes
Tube Rack Tile Potato Distilled water
Ruler Measuring cylinder Masking tape
Glucose solution Siv Paper towel
P6a Prediction and theory
My predictions are as you decrease the glucose concentration the size of the potato will increase. As you increase the glucose in the solution the water concentration will decrease.
This means the water concentration is higher inside the potato therefore water will diffuse across the cell membrane of the potato into the solution. This will cause the potato to shrink. When the potato shrinks we say it has become flaccid and if the water concentration is greater outside the potato the water will diffuse into the potato causing it to become (turgid) an increase in size.
P6b Number of readings and appropriate range
In conducting this experiment I will use a range of at least five different concentration and at least 2 readings to show I repeated the experiment. I took 2 readings and this gave me the average change in length and average percent change in length.
Table on other the side
P8a Extended Theory
Test tube A will decrease in length, as there is a strong solution. So the water enters out of the chip in to the stronger solution as osmosis is occurring. There is a high concentration of water in the chip so the water will leave he potato to a low concentration (where there is less water). This causes the chip to shrink.
Using a wider range will provide evidence what will happen when the water concentration is equal on both sides of the semi permeable membrane. The range I used was suitable as this gave me a more reliable result then if I just used a smaller range. I used 3cm of chips as they are easy to fit in to the tubes and the length was enough to observe the chips. I think that repeating is an important part in my investigation, as it will make my results more reliable.
The semi permeable membrane is important in this investigation because it holds the cell together and also controls the amount of water that is coming in and out.
The change in the cell gains water and it will swell and becomes turgid and if it loses water in becomes flacid. It will only become turgid if there is more water in the solution and it will only become flacid when there is a strong glucose solution. However the ways the water that will not leave the solutions is when there is a weak solution and also if there is the same concentration and in the water, water will not leave the solution.
Analysis
A2a What I found out
I discovered that if I increase the amount of water the length of the chip will increase in size and if you increase the amount of glucose the length of the chip will decrease.
A4b Pattern or trend
As the morelaritie of the glucose solution increases, the length of the potato chip decreases.
A6b Conclusion
From my graph I discovered that the more volume of glucose decreases my initial length and the more volume of water increases my initial length. And I also found out that 30ml of water and 10ml of glucose has no change at all (No change in initial length, final length). I also found out how to work out my average change in length (percentage change in length x 2= answer / 2)
A6b conclusion and scientific theory
I discovered that if a cell is placed in a strong solution the potato chip will shrink and if the cell is in a weak solution the potato chip would grow. But if the cell is in the same concentration the potato chip will stay the same size. The movement of water depends on the differences in water concentration on either side of the semi permeable membrane because there is a greater water concentration inside the chips in the strong solution; the chips have lost water causing it to decrease in length. If there is weaker water concentration inside the chips in the weak solution, this will cause the chips to gain water and increase in size.
A8a Detailed scientific knowledge to explain conclusion
