Distilled water has a higher water potential. It would be less of a negative water potential then in say... potato cells. Therefore, it diffuses in by osmosis, and the potato cells would swell and become turgid.
Turgid is once again, another one of those happy words that examiners would seem to dote on. xP
Yay. (:
Sucrose has a lower water potential then in the same potato cells, therefore, water would diffuses out of the potato cells by osmosis, and the cells will shrink and become plasmolysed. (Yes, that is another of those 'words'.)
Anymore water diffusing in by osmosis on a cell that has reached maximum turgidity will be forced the opposing pressure of the cell wall.
In sucrose, little or no water would remain in these potato cells. The cell wall would not be able to shrink any further.
The rate of change would be determined from an initial part of a graph as the initial part is linear, so it will be constant, and as time goes on the water potential of the cell will change and therefore slow, so it would be easier to compare all from the beginning.
Active Transport :
With diffusion, osmosis and facilitated diffusion, they are all passive, and it moves in/out of the cell. Active transport is different in that it is not passive, it requires ATP (see previous posts), it is definitively more complex, and it goes against a concentration gradient.
It is carrier assisted, which means protein carriers are present. It requires energy to move the molecules against their concentration gradient.
What whats to go through, fits on to the carrier with the specific gap/shape. The ATP comes along and splits into ADP + Pi + energy. The energy attaches and changes the shape, and then the thing that wants to go through goes through.
Endocytosis means going in ti the cell. If it is a solid it is called phagocytosis, and if it is a liquid/fine suspension, it is pinocytosis. Exocytosis means going out of the cell.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment