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Alevel biology understanding

I'm revising biological molecules at the minute using the 'blue man' and he says 'glucose is highly soluble in water. Because of this, a high concentration of glucose in a cell would cause water to enter by osmosis'.
Now maybe it's just late but could someone tell me if I understand this right?
On the one hand I'm thinking that if glucose is soluble then surely IT enters the water... not the water entering the cell TOWARDS the glucose.
But my knowledge of osmosis tells me that water diffuses from higher concentrations of water to lower concentrations of water.
Is it just that the glucose is taking up more space than water within the cell and since there is a higher concentration outside of the cell it enter in? And that's why it's considered soluble?

If you read all of that and are willing to answer, thanks.
Reply 1
Original post by Stefani.r
I'm revising biological molecules at the minute using the 'blue man' and he says 'glucose is highly soluble in water. Because of this, a high concentration of glucose in a cell would cause water to enter by osmosis'.
Now maybe it's just late but could someone tell me if I understand this right?
On the one hand I'm thinking that if glucose is soluble then surely IT enters the water... not the water entering the cell TOWARDS the glucose.
But my knowledge of osmosis tells me that water diffuses from higher concentrations of water to lower concentrations of water.
Is it just that the glucose is taking up more space than water within the cell and since there is a higher concentration outside of the cell it enter in? And that's why it's considered soluble?

If you read all of that and are willing to answer, thanks.


I used to get confused about this quite a bit and one of my A-Level Biology teachers told me to think about it as water moving from an area of lower solute concentration to an area of higher solute concentration, instead in terms of water concentrations. In my mind, I pictured it as having to make the concentrations of the solutes the same, so it was almost like the water was "diluting" the cell so to speak when there was a high glucose concentration, to make to equivalent to the concentration outside of the cell, if that makes sense. Glucose is also soluble in water because it is small and has polar groups, so can form hydrogen bonds with water (I don't know if you need to know that for your specification, but I did Salters Nuffield A-Level Bio and I remember that being included with info on the properties of water in Year 12) (I also do Chemistry where this is also discussed) Hope this at least kind of makes sense!
Reply 2
Original post by aarynmb
I used to get confused about this quite a bit and one of my A-Level Biology teachers told me to think about it as water moving from an area of lower solute concentration to an area of higher solute concentration, instead in terms of water concentrations. In my mind, I pictured it as having to make the concentrations of the solutes the same, so it was almost like the water was "diluting" the cell so to speak when there was a high glucose concentration, to make to equivalent to the concentration outside of the cell, if that makes sense. Glucose is also soluble in water because it is small and has polar groups, so can form hydrogen bonds with water (I don't know if you need to know that for your specification, but I did Salters Nuffield A-Level Bio and I remember that being included with info on the properties of water in Year 12) (I also do Chemistry where this is also discussed) Hope this at least kind of makes sense!

ah ok, it's easier to comprehend when thinking about it in the way you just described. Thank you :smile:
Reply 3
Original post by Stefani.r
I'm revising biological molecules at the minute using the 'blue man' and he says 'glucose is highly soluble in water. Because of this, a high concentration of glucose in a cell would cause water to enter by osmosis'.
Now maybe it's just late but could someone tell me if I understand this right?
On the one hand I'm thinking that if glucose is soluble then surely IT enters the water... not the water entering the cell TOWARDS the glucose.
But my knowledge of osmosis tells me that water diffuses from higher concentrations of water to lower concentrations of water.
Is it just that the glucose is taking up more space than water within the cell and since there is a higher concentration outside of the cell it enter in? And that's why it's considered soluble?

If you read all of that and are willing to answer, thanks.


When you have glucose (a type of sugar) in water, it mixes very well and spreads out evenly in the water.
Now, about osmosis - it's like water moving through a tiny gate. It likes to go from where there's more water to where there's less water.
So, if there's a lot of glucose inside a cell and not as much outside, the water will go into the cell. This happens because there's more glucose inside the cell, and water goes where there's less of it to balance things out.
So, it's not glucose pulling water in. Instead, it's the fact that there's more glucose inside the cell that makes water go in. This happens because glucose takes up space, and that makes the water move into the cell. This happens because glucose can dissolve well in water.

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