osmosis help

Hey guys!
I was answering a paper 1 Biology OL exam when i figured out i have this annoying problem with osmosis !
now i know very well the definition is : movement of water molecules from region of high water potential to region of lower water potential down concentration gradient.

the effect of osmosis on plant cells is that they leave the plant cells turgid when left in a dilute solution <-- i don't understand this ! How ? doesn't dilute mean low concentration ? then isn't it supposed to move from inside the cell to the outer solution ?
does this mean that the lower the concentration , the higher the water potential ? I'm really confused :frown:

This really confuses me and it makes me fall into mistakes all the time , any help please ? I'd appreciate it !
I know i got something very mixed up , would someone clear it out for me ?

(edited 11 years ago)

Reply 1

techno836

20

Original post by moushiramagdy

Hey guys!
I was answering a paper 1 Biology OL exam when i figured out i have this annoying problem with osmosis !
now i know very well the definition is : movement of water molecules from region of high water potential to region of lower water potential down concentration gradient.

the effect of osmosis on plant cells is that they leave the plant cells turgid when left in a dilute solution <-- i don't understand this ! How ? doesn't dilute mean low concentration ? then isn't it supposed to move from inside the cell to the outer solution ?
does this mean that the lower the concentration , the higher the water potential ? I'm really confused :frown:

This really confuses me and it makes me fall into mistakes all the time , any help please ? I'd appreciate it !
I know i got something very mixed up , would someone clear it out for me ?

dilute means more water !!!!! it is the water that moves not anything else :biggrin:

... hope this helps sort of :-)

Reply 2

moushiramagdy

OP

well yes , the concentration becomes lower because water is added :biggrin:

Reply 3

Josh93

11

Dilute means that the concentration is lower/there are more water molecules relative to solute molecules therefore as far as I understand it there should be a net movement of water into the cell until the solution becomes isotonic, which will probably result in the cell becoming turgid if it has a cell wall or possibly rupturing if it doesn't.

You're getting confused on concentration (you're right in thinking that dilute means a lower concentration but only in terms of solutes, a dilute solution will have a higher concentration of water and therefore a higher water potential) I think - water will diffuse across a partially permeable membrane to an area of lower water concentration or higher solute concentration, does that help?

Higher water potential = higher concentration of water/less solutes
Lower water potential = lower concentration of water/more solutes

Hope that helps :smile:

Edit: sincerely hope that I'm right, it's been a year since I've done osmosis :s-smilie:

(edited 11 years ago)

Reply 4

Taj13

2

Original post by moushiramagdy

Hey guys!
I was answering a paper 1 Biology OL exam when i figured out i have this annoying problem with osmosis !
now i know very well the definition is : movement of water molecules from region of high water potential to region of lower water potential down concentration gradient.

the effect of osmosis on plant cells is that they leave the plant cells turgid when left in a dilute solution <-- i don't understand this ! How ? doesn't dilute mean low concentration ? then isn't it supposed to move from inside the cell to the outer solution ?
does this mean that the lower the concentration , the higher the water potential ? I'm really confused :frown:

This really confuses me and it makes me fall into mistakes all the time , any help please ? I'd appreciate it !
I know i got something very mixed up , would someone clear it out for me ?

Dilute means that the solution has more water molecules than solute molecules. The solution would then have a higher water potential compared to that of the cytoplasm. Thus, the water molecules would move into the cytoplasm of the cell which has a lower water potential, causing the cell to become turgid.

This was posted from The Student Room's iPhone/iPad App

Reply 5

moushiramagdy

OP

Original post by Josh93

Dilute means that the concentration is lower/there are more water molecules relative to solute molecules therefore as far as I understand it there should be a net movement of water into the cell until the solution becomes isotonic, which will probably result in the cell becoming turgid if it has a cell wall or possibly rupturing if it doesn't.

You're getting confused on concentration (you're right in thinking that dilute means a lower concentration but only in terms of solutes, a dilute solution will have a higher concentration of water and therefore a higher water potential) I think - water will diffuse across a partially permeable membrane to an area of lower water concentration or higher solute concentration, does that help?

Higher water potential = higher concentration of water/less solutes
Lower water potential = lower concentration of water/more solutes

Hope that helps :smile:

Edit: sincerely hope that I'm right, it's been a year since I've done osmosis :s-smilie:

Ohhh , I get it now , thank you ! :biggrin:

I think you did haha :smile:

Dilute means that the solution has more water molecules than solute molecules. The solution would then have a higher water potential compared to that of the cytoplasm. Thus, the water molecules would move into the cytoplasm of the cell which has a lower water potential, causing the cell to become turgid.

aha , alright thank youu :smile:

Reply 6

Josh93

11

Original post by moushiramagdy