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samsonmoley
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:secruity: pleaseeeee help me
ok so ve done an experiment of a potatoe tubes in different concentration of salt solutions for as level biology in order to find the water potential of the potatoe in question and ive got the results and ive done the graph of concentration to %change of mass and its an s shape but what does it all mean is it that the water potential is where it crosses the concentration? and what do i do next? do i have to do something with the solute potential of salt solution or am i just making this way harder than it needs to be? now i no thats way way to many questions in one go but im completely stuck and someone out there in this vast universe must have done this experiment before mustnt they?
please help!
diolch yn fawr
Zoe :bootyshak
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Twiglet
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potato !
what is the question you are answering? or maybe im guessing this is coursework...
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samsonmoley
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tis to find the water potential of a potatoe using different conecntrations of salt solutions and through osmosis - its biology coursework - im doing distance learning -
IM SO ALONE - im going mad
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spin
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Potato!! No matter how much salt you add it will never ever gain an "e" !
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~Kyra~
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(Original post by samsonmoley)
:secruity: pleaseeeee help me
ok so ve done an experiment of a potatoe tubes in different concentration of salt solutions for as level biology in order to find the water potential of the potatoe in question and ive got the results and ive done the graph of concentration to %change of mass and its an s shape but what does it all mean is it that the water potential is where it crosses the concentration? and what do i do next? do i have to do something with the solute potential of salt solution or am i just making this way harder than it needs to be? now i no thats way way to many questions in one go but im completely stuck and someone out there in this vast universe must have done this experiment before mustnt they?
please help!
diolch yn fawr
Zoe :bootyshak
Yep I've done this experiment! Basically, due to water potential being where water moves from a higher concentration to a lower one, (osmosis and all that) its all about which direction the water moves in. Inside the potato cells is water, and outside them (in your test tubes) there is your salt solution which has some water molecules, and some salt molecules. In high concentrations of salt solution, there are much fewer water molecules than there are inside the cell. So by osmosis, the water moves OUT of the cells. This makes the potato shrink a bit (thereby losing mass) In really low concentrations of salt solution, there are more water molecules inside the cell than in the solution, so the water moves IN to the cells. They then gain mass.

This means that at the point where the potato doesn't change in mass, the solution must be the same concentration as inside the potato, as water isn't moving in or out.

I'm not sure what you do next, as that's where I stopped, I just did about a million more graphs then wrote it up. Oh and I used sugar solution but the principle should be the same. Hope I've helped a bit! Oh yeah and potato is spelt with no e
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rainjan_4now
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(Original post by samsonmoley)
:secruity: pleaseeeee help me
ok so ve done an experiment of a potatoe tubes in different concentration of salt solutions for as level biology in order to find the water potential of the potatoe in question and ive got the results and ive done the graph of concentration to %change of mass and its an s shape but what does it all mean is it that the water potential is where it crosses the concentration? and what do i do next? do i have to do something with the solute potential of salt solution or am i just making this way harder than it needs to be? now i no thats way way to many questions in one go but im completely stuck and someone out there in this vast universe must have done this experiment before mustnt they?
please help!
diolch yn fawr
Zoe :bootyshak

basically, from your graph, you should be able to work out, roughly, the water potential of the potato as you increase the amount of salt in the solution.

i'm not sure of you axis' but i can say that at low salt concentrations, water will be moving into the potato, and at high salt concentrations, water will be moving out of the potato. Therefore you have to identify the point where water stops moving into the potato (increasing the mass), and starts moving out. that point is balance between concentrations- and i think you should be able to work out that if there is a balance then that should be the water potential of the potato in question BUT I MAY BE WRONG, I AM REALLY JUST KIND OF GUESSING! :confused:

heres some notes on osmosis to help you, along the way:


-water potential is the solvent (water) concentration in relation to solute (i.e. sugar) concntration.

i-f sugar/glucose molecules occupy the majority of a solution than water molecules do- that solution is said to have a low water potential.

-osmosis if the movement of water from areas of high water potential to areas of low water potential.

-so basically, if your potato cells have a high solute concentration, pure water will move into potato cells, increasing the weight of the potato. But if you use salt water, the reverse should occur- where water moves OUT of the potato cells, decreasing the mass of the potato.



hope some of that helps
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samsonmoley
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yay yay i got a reply thank god that was uselful im into science im not a novelist im allowed to spell badly - infact i cant spell - dont hold it against me generally i use spell check but today nahhhhhh - HAVE YOU EVER SEEN A DOCTORS WRITTING :eek: I SURPRISED WE ARE NOT ALL DEAD!
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