IB Biology osmosis IA Help

[khalid]

What graph will show my Biology lab results more clearly, line graph or bar graph?

Edited August 27, 2012 by khalid

[Mahuta ♥]

Well this experiment is sort of trying to show you how the cells react to different concentrations in the blood. There isn't an exact way to do it actually, so size and concentrations can change.

You have to use cubes, or little pieces of potato..or whatever shape as long as they're all the same. You have to prepare different concentrations of sugar solution. It could be

0% (water only), 25% (25ml sugar, 75ml water), 50% (50, 50), 75% (75ml, 25ml), 100% (100% sugar).

or

0%, 20%, 40%, 60 %, 80% and 100%.

The only difficult part in this is making the solution for the first time. You should be given the starch or glucose solution by your teacher. That solution is 100% so you can take 3 samples from it (or enough for the number of trials you're doing). The 75% is, as I said above, 75ml of sugar solution (the 100% one) and 25ml distilled water. So, you just take 75ml of the sugar solution and add 25ml of distilled water. Like with the first one, make 2 or 3 for your trials.

If you want say..40ml instead of 100ml, then the same ration stands:

for 25%: 10ml sugar and 30ml water. For 20%: 16ml sugar and the rest water.

Basically 40ml/ 4 (if you're using 25,50, 75) = 10, then that * 2 (for 50%, or 4 for 75%). You get my point.

The whole point is to see the different in the mass of the potato before you put it in the solution and after you put it in the solution (for a few hours, but no more than 24).

[khalid]

So where do i put the potato and the solution?

[dessskris]

on a petridish

[Mahuta ♥]

Or a test tube, it doesn't really matter.

[Nea Lumina]

First, the potato was cored, 24 cores of 2.0cm were made from the #5 corer, two cores were washed to rid of any excess membrane that could affect the results, the cores were then dried and weighed using a digital scale (masses recorded in a table) then placed in a test tube containing the sucrose solution (10mL ±0.1mL) and either labelled group ‘A’ or ‘B’ there were 2 test tubes per sucrose concentration.

The potatoes were left in the solution for eleven and a half hours before being removed, washed to rid of any excess sucrose that could affect the mass, dried and weighed. Results were recorded in a table.

The delta mass was then determined by the change in mass over time (initial mass-final mass) and converted into a percentage; this was then displayed in a graph against sucrose concentration.

This was how I did my Osmosis lab...