Need help with a lab on osmosis!

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MariaKsk88
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Need help with a lab on osmosis!

Post by MariaKsk88 » Sat Dec 03, 2005 11:04 am

Hey!

I did a lab to explore osmosis the other day and I have a question for you guys, if you wouldn't mind helping me out. What I did was basically to look at two different ways that osmosis works by putting a piece of raw potato in pure water and another one in water with starch in it. My hypothesis is that the potato in the pure water will get bigger and the other one will get smaller.. But then the teacher said we need to have a control, what could that be in my case? A piece of potato that I don't put in water at all??

I'd really appreciate some help!

/Maria

th1_rhs13
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Post by th1_rhs13 » Sat Dec 03, 2005 12:54 pm

You need to specify which is needed + or -.

A Positive control is one that is self-evident or known and can allow one to draw contrast to your actual results.

http://en.wikipedia.org/wiki/Positive_control

MariaKsk88
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Post by MariaKsk88 » Sat Dec 03, 2005 4:03 pm

Well, he didn't say so I'm guessing it doesn't matter which kind of control it is. We're not very advanced in biology... ;)

Plexxi
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Post by Plexxi » Sat Dec 03, 2005 7:12 pm

i did an osmosis lab the other day with decalcified eggs, and one broke on me! :!:

Sabby
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Post by Sabby » Sun Dec 04, 2005 7:37 am

In your experiment you need a control. Since you're finding the effect of hypertonic (the sugar solution) vs. hypotonic (pure water) solutions on potatoes, you'll need an isotonic solution as a control (that is, a solution that has the same concentration of water so there is no gradient). Your lab is so standard that you can probably google it~
APOPTOSIS BOOOOOOOM!

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Navin
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Post by Navin » Sun Dec 04, 2005 8:17 am

What about boiling the potato so that the partially permeable membrane would be destroyed?
Botany is the study of what? Bottoms!

MariaKsk88
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Post by MariaKsk88 » Sun Dec 04, 2005 12:12 pm

Sabby wrote:In your experiment you need a control. Since you're finding the effect of hypertonic (the sugar solution) vs. hypotonic (pure water) solutions on potatoes, you'll need an isotonic solution as a control (that is, a solution that has the same concentration of water so there is no gradient). Your lab is so standard that you can probably google it~


That does make sense, but how do you know when the solution has the same concentration as the potato? Oh and by the way, we used starch, not sugar.

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Post by Sabby » Tue Dec 06, 2005 2:31 am

we used lab equip to find the concentration of starch necessary for no osmosis to occur, in your case, using a medium amount of starch could work as your control
APOPTOSIS BOOOOOOOM!

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