class 4

      In biology class, we discussed and observed diffusion and osmosis occurring in cells and water in an experiment. We learned that diffusion is the net movement of molecules down their concentration gradient while osmosis is the movement of water through a selectively permeable membrane from a region of its higher concentration to a region of its lower concentration. Molecules can move in both directions in and out of the membrane, as long as it is permeable to the molecule. Types of solution such as hypertonic, hypotonic, and isotonic have different affects to the membrane. A hypotonic solution has lower solute concentration, but hypertonic has higher solute concentration as water moves inside both the bag and beaker. On the other hand, isotonic solutions have equal solute concentrations. The class split into groups of four and started experimenting using "cell membranes", solute with different molarities, and water to find the molarity and any changes in the cells mass.We made six different cells filled with 7ml of solution, each with a different molarity, and measured them before we put each in a cup of water. Then after about 30 minutes we took the membrane out of the water, dried it and then massed it one more time to determine it's mass change and molarity. Our results for the molarities of the solutions were; Blue:0 Clear:0.2 Green:0.4 Yellow:0.6 Purple:0.8 Red:1.0
     Then we tested diffusion and osmosis with potatoes. First we skinned russet potato and then tested the amount of sugar the potato contained. We cut the potato into 24 pieces and put 6 in each cup filled with different solution. That night we recorded the change in size and mass of the potato to see if it got smaller or bigger.  The potatoes mass increased.