Most Sought After Biology Notes

Most Sought After Biology Notes

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Sunday, 26 January 2014

Understanding Osmosis 2

Last post I explained the osmosis outline. Now we shall go in detail regarding the process, as shown below:

click to enlarge

As you can see, water loves to go to the 'pekat' (浓缩) region. From this principle, we shall understand the 3 conditions occurred in red blood cells and plant cells, as mentioned in the experiment result shown below:

click to enlarge
How to explain in exam to get full marks:

When immersed in hypertonic region:
-The solution is more concentrated than the cell sap (1 mark)
-As a result, water diffuses from the cell sap into the solution (1 mark).
-The net flow is negative, as the water flows out of the cell (MUST MENTION THIS!) (1 mark).
-Hence, the cell mass decreases, and flaccid/ crenation occurs (1 mark).

When immersed in isotonic region:
-The solution's concentration is similar to the cell sap (1 mark)
-As a result, water diffuses equally in & out of the cell (1 mark).
-This is because the net flow is zero (MUST MENTION THIS!) (1 mark)
-Hence, the cell mass does not change. (1 mark).

When immersed in hypotonic region:
-The solution is more diluted than the cell sap (1 mark)
-As a result, water diffuses from the solution into the cell sap (1 mark).
-The net flow is positive, as the water flows into the cell (MUST MENTION THIS!) (1 mark).
-Hence, the cell mass increases, leading to haemolysis/ cell turgidity (1 mark).

RESPECTO :-)

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