In an experiment to understand osmotic potential in cells...

In an experiment to understand osmotic potential in cells you set up the following experiment. You prepare 3 bags made of dialysis tubing that is permeable to water but not to glucose or anything larger than glucose by first adding 9.5 ml of water. To these tubes you then add either: Bag A - 0.5 g glucose (molecular wt. ~180 daltons per molecule) Bag B - 0.5 g of egg albumin (a water-soluble protein, each molecule weighs ~45 kilodaltons) Bag C - a single glass bead that weighs 0.5 grams After weighing the dialysis tubing bags you add them to a beaker of distilled water and let them sit for two hours at room temperature (25 degrees Celsius). After two hours you record the following:

Transcript

00:01 In this experiment, we are looking at the osmotic potential of cells.

00:05 In kind of three little scenarios we set up in bags that are going to represent ourselves with different concentrations.

00:12 So in bag a, we have a 0 .5 % glucose solution within a bag and with that 9 .5 mls of water.

00:25 And then in bag number b, we have 0 .5 ag albumin.

00:30 With again 9 .5 mls of h2o.

00:34 And then we have bag number c, which has a single glass bead weighing 0 .5 grams with 9 .5 emels of water in that one.

00:44 So we are going to go through and look at our variables and how they compare with the weight change based on the principles of osmosis and diffusion.

00:54 So when we're looking at the independent variable, so i always like to remember independent variable as in i so i an independent is what i control um so essentially things that we are controlling in this experiment or what we are changing um so essentially we are controlling or changing the what will be known as the solute within the bag um so independent variable is going to be your solute type egg albumin for our bead and we're also controlling what the weight is at the start because we are choosing to use 9 .5 amounts of water and then 0 .5 glucose and egg albumin to essentially get 10 mls a consistent number in our kind of fake cell.

02:05 So dependent variable is what is going to change based on the independent variable.

02:10 So in this experiment, our dependent variable is going to be our weight at the end.

02:20 And with that, we can also say what our weight change is.

02:27 And that is because our weight at the end, as we will see, is going to rely on our independent variable and those factors.

02:37 And then for a control variable, obviously bag number c is going to represent our control.

02:45 Due to the fact that we only have a glass bead.

02:49 So no water osmosis is going to be occurring.

02:53 That is just going to give us a stable weight at the start and weight at the end.

02:56 And another control for the fact that this experiment for all three bags is going to be done under conditions of 25 degrees celsius.

03:06 So that is kept consistent throughout all three bags.

03:11 So then to go ahead and answer the rest of our questions and to understand what is happening exactly.

03:18 Essentially, both of our bags are being placed in a solution of water.

03:23 So on the outside, we're going to have 100 % h2o.

03:30 And following our laws of osmosis and diffusion, water is going to diffuse from areas of high concentration to low...

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