Confusing AS osmosis question?

Question

Ok, sorry but this is in 4 parts, but i really need some help on this as its revision for my exam in a few weeks! Thanks:

So basically we have a cell in solution, and the cell contains the following: Sucrose 0.20, glucose 0.01, fructose 0.01, maltose 0.01 and outside the cell and in the solution there is sucrose 0.65 and glucose 0.04.

(i) which sugar(s) will move out of the cell?
(ii) Which sugar(s) will move into the cell?
(iv)Explain why the volume of the "cell" would change during the experiment (4 marks).

Thank you very much for your time and help,
Jon

Answer 1

We are talking about a living cell right?
Remember that the membrane is semi-permeable but the movement of solutes is controlled by the cell.

i) NONE will move out. There is maltose and fructose only inside the cell so yes the spontaneous thing would be for them to diffuse out of the cell. However the cell will not allow valuable nutrients to escape (otherwise for example it would be losing ATP, NADH, etc and wouldn't be able to function)

ii)Sucrose and glucose have a higher concentration outside the cell, thus they will tend to diffuse in the cell. This doesn't occur randomly but through facilitated (and regulated) diffusion.

iv) The solutes that contribute in the osmotic pressure are the ones that CANNOT pass through the membrane. Sucrose and glucose will NOT contribute since they will diffuse into the cell until they reach the same concentration as in the outside of the cell. Fructose and maltose are held within the cell, thus they contribute to the osmotic pressure (together with the rest of the cell components). This means that the cell has higher osmotic pressure than its environement and it will gain water; thus it will swell.

Answer 2

The answer for (i) is that fructose or maltose is going to move out of the cell. Because the amount of fructose or maltose outside the solution is 0.
(ii) Sucrose or glucose can move into the cell. Because the concentration inside is less then the outside one.

and i don't know the ansewr for number 3. sorry.

Answer 3

i. Fructose and maltose will move out of the cell. This is because these sugars are not present in the outside solution and their concentration is said to be zero.

ii. Sucrose and glucose will move into the cell. This is because the concentration of these sugars in the outside solution is higher than the concentration in the cell itself.

iv. The volume of the cell would change as various volumes of sugars would move in and out of the cell.

Answer 4

If this is for osmosis, you should be asking about the water, not the sugar. Osmosis is about water. :)