GCSE Biology: Osmosis in a Potato
Aim
To investigate the effect of placing a piece of potato in a given strength of sugar solution.
Prediction
I predict that, as the solution becomes more concentrated the more the cell will shrink, as the water, of higher concentration inside the potato cells, flows down a concentration gradient into the solution, which has a lower concentration of water molecules. If we say that the percentage change when the potato is placed in the 1M solution is x%. I predict that when the solution is 0.5M the percentage change will be 0.5x%, and when the solution is 0.25M strength I hypothesise the change will be 0.25x%.
Variables Description: Dependant Variables
The dependant variable is plotted on the y-axis. In this experiment this is the change of mass of the potato when it is placed in different strengths of sugar solution.
Variables Description: Independant Variables
The independant variable is plotted on the x axis and is what you choose to change in the experiment. In this experiement it is the strength of the sugar solution.
Variables Description: Constant Variables
These stay the same all the way through the experiment and are the fair test rules. In this experiment that are that the amount of sugar solution used must always me 10.0ml. This is to be placed into the test tube. The solution needs to always be at the same temperature. We will make sure that all experiments are at 20 degrees centigrade before we start the experiment. The size of the potato sample that we place into the solution also needs to be kept constant. A mass of 2.5-2.6g is sensible. The diameter is fixed as the potato cork borer always measures to the exact same measurement. We also needs to make sure that the potato is left in the solution for the same time, 30:00 minutes.
Equipment
• Potato
• Standard Sugar Solution
• Wash Bottle
• Test Tubes and Test Tube Rack
• Cork Borer
• Scalpel
• Cutting Board
• Scales accurate to 2.d.p
• 10ml Syringe
• Paper towels
• Ruler
• Stop Watch
Method
1. Firstly, the cork borer needs to be used to cut out a piece of potato at least 4 cm in length. This allows room for trimming off untidy edges.
2.
3. On the cutting board the cylindrical piece of potato needs to be cut to 35mm. Using a ruler, measure this as accurately as possible and cut the potato to 35mm in length using a scalpel.
4. Using the scaled weigh the potato to 2.
way. I will put each piece of potato into the 5 test tubes and add the
B will have this size potato in but cut in half and Test tube C will
Conclusion In my conclusion, the potatoes with the lowest concentration gained the most mass, and would become hard relating back to the Turgor theory I stated earlier. In contrast to this, the potatoes in the most concentrated solution lost the most weight thus becoming plasmolysed and limp also relating back to the background I have mentioned earlier. Evaluation In general the experiment was succesful the results were consistent and also were in accordance with the theories made at the start.. The experiment could have been improved by: · More subjects used instead of potatoes · More potatoes · Wider time ranger · Different molarities Using this variety of methods could have improved the experiemnt, however I was generally satisfied with the results of this osmosis experiement.
We then cut our potato tubes with the cork borer and cut them with the scalpel so they were the same length and weighed them. We then put one potato tube in each test tube and then added the same amount sugar solution in to each tube. The concentration of sugar solutions varied in each test tube.
Materials used in the experiment included 5-7 g of the potato tissue, 50ml of 2.0M phosphate buffer coffee filter and guaiacol dye.
The purpose of this experiment is to investigate the effect of changing the concentration of sodium chloride solution on the rate of osmosis in tubes of potatoes. This was maintained using equal measurements of the potato tubes and applying them into the different concentrations of sodium chloride, 0%, 2%, 5%, 10%, 20% and 26%, in beakers then measuring the change in mass of the potato tubes afterwards. The time taken for all potato tubes to be placed in solution was 15 minutes. Can the concentration gradient of the sodium chloride solution influence on the rate of osmotic diffusion undergone by the potato tubes?
potato chips left in a sugar solution for a period of 1 hour. I will
So the experiment will be based upon the movement of water. The first potato chip will be placed in a zero percent solution. I believe that this will increase the mass. I believe this because the zero percent solution has a lower concentration than the cell sap inside the potato. The potato takes on the water through osmosis and the cell pushes out from inside the cell making it swell and become more rigid.
cork borer and a ruler. I will keep the potato chips the same size in
To investigate the osmotic effect of changing the concentration of sucrose solution; distilled water, 20% sucrose solution, 40% sucrose solution, 60% sucrose solution on the change in mass of potato cylinder after 30 minutes of being in solution.
Conclusions: There is a pattern on the graph, and data table, which shows that as the concentration of the sucrose solution increases, the potato's percentage change in mass decreases.
Diagram:.. Variables:.. I am making variables in only one field. I am changing only the concentration of the salt solution.
...ore reliable if it were possible to do more trials to make sure that the data that was found was correct. This experiment could’ve been more reliable if some mistakes weren’t made like, the inaccuracy of weighing and measuring the potatoes. This could have affected the results by throwing off all the data and giving numbers that were nowhere near accurate. Another mistake that could’ve been made was the amount of solution put into each test tube. Some of the test tubes may have had to little or not enough of its solution. Some ways to fix both of these problems would be to weigh and measure each potato core more than once which is not what was done. A way to fix the inaccuracy of the amount of salt water put into each test tube would be to measure the solutions into a different container to make sure it’s an accurate measurement, then pouring it into the test tube.
4. Put each group of potato discs in one of the 6 test tubes and watch
The Effect of Salt Solution Concentration On The Mass Of Potatoes Introduction = == == == ==