Heyy, So I did a prac which tesed osmosis and simple diffusion. Basically a solution consisting of NACI, starch, glucose and protein was placed in a tubing and then into water. I had to write a summary of results, hypothesis , IV & DV ( I didn't find IV), errors and limitation and conclusion. I will place my criteria could u see if I got everything covered to get 25 marks out of 50 ( the other 25 marks are for the other prac) thank you.
Summary of Results:
[/b][/u]
Solution A composed of NaCl, Glucose, Starch, and protein was placed in a cellulose tubing and suspended in Dh20, water. Before dialysis, the Dh20 showed no signs of any of the Solution A molecules being present. However, after dialysis, there was a change in the presence of solutes inside and outside the tubing; as NaCI and glucose were detected by specific test reagents outside. NaCl was tested by silver nitrate, and white precipitation occurred confirming NaCl presences. While the uristix changing its color confirmed the presence of glucose.
Simple diffusion is the NET PASSIVE (requires no cellular energy) movement of small polar molecules and hydrophobic molecules like water and carbon dioxide from a region of high concentration to a region of low concentration and therefore, smaller polar molecules like glucose and NaCI were able to pass through the cellulose tubing (semi-permeable membrane), from inside the tubing (high conc) to outside H20 environment. While larger molecules like protein, starch, were inhibited from passing through cellulose tubing. NaCl and glucose can diffuse through the membrane until the concentration of NaCl and glucose inside the tubing and outside the tubing reach and maintain equilibrium
Additionally, before dialysis, the bag was weighed as 17.1g and after dialysis, the weight of the bag was 18.4g, There was a difference of 1.3g. The weight was scaled by measuring scale. Increase in weight of the bag shows evidence of osmosis occurring. Free water molecules net passively moved from outside the tubing (high concentration of free water molecules or low concentration of solutes) into the tubing containing solution A (low concentration of free water molecules or high concentration of solutes) resulting in the tube gaining more weight. The water moved down the concentration gradient. The tubing was placed in a hypotonic solution. Weight gain of the tubing occurred for every investigation participated in the class highlighting a trend.
Overall, The purpose of the investigation was to test the permeability of Solution A (glucose, starch, NaCl and protein) inside the tubing to the water on the outside and also, to see the effects of osmosis. Glucose and NaCl were identified as permeable.
Conclusion:
[/b][/u]
It was concluded that the dialysis tubing doesn’t allow all kinds of substances to pass readily through the pores of its membrane. This means that it is selective in its permeability to substances. The dialysis tubing was permeable to glucose and NaCl and free water molecules but not to starch and protein. Starch and protein was excluded because it has a larger molecular size.
ERROR AND LIMITATION Error: Temperature - The temperature wasn't controlled. The temperature has an effect on simple diffusion. A higher temperature increases the average kinetic energy of a particle therefore causing it to move faster at a quicker rate → increasing rate of diffusion. This affects results
Error: Miscalculation in weight- due water loss from the cellulose tubing becaus an accidental puncture. Affected result from inaccurate as unable to clearly show how much water came through from osmosis?
.
Limitation: Lack of repeated trials/repetition of experiment- due to less time the experiment couldn’t be repeated several times to check its accuracy and reliability. Repetition of the investigation should be necessary next time to ensure NaCI and glucose were present and simple diffusion occured.
HYPOTHESIS
It is predicted that , if a bag containing solution A is placed into a solution/environment with higher concentration of free water molecules (distilled H2O solution) then there would be an increase of size and weight of the bag due to osmosis. Additionally, It is predicted If movement of molecules via simple diffusion occurs, then there would be a change in presence of molecules inside and outside of the bag after dialysis. Small molecules including Nacl and glucose would be occurant outside due to size.
PLEASE CORRECT IT AND TELL ME WHAT I SHOULD ADD AND IF YOU NEED MORE INFO
Home
Help
Search
Login
