Question

Describe the movement of water when a cell is placed in an isotonic, hypertonic and hypotonic solution. Explain the effects each type of solution has on a cell (6pts)

Answer 1

The cell has a specific osmolarity 300 mOsmol. But in case of various conditions the cell may undergo exosmosis or endosmosis. This depends on the molarity of the extracellular fluid present around the cell.

So there can be 3 conditions of water movement in cell. Weather the water will enter the cell, exit the cell or no movement of water may occur.

In case of isotonic condition :-

Isotonic solution means a solution that has the similar osmolarity as the fluid present in the cytoplasm of the cell. If a cell is placed in an isotonic environment or solution there will be no movement of water into or outside the cell. Since no concentration gradient is formed between the cytoplasm and the isotonic solution involvement thus there will be no osmosis. The cell will neither shrink nor become turgid it will remain in its usual shape and size as it was placed.

In case of hypertonic solution :-

Hypotonic solution is a solution that has higher osmotic pressure as compared to the cytoplasm of cell. Thus if a cell is placed in a hypotonic environment then exosmosis occurs. It means that the water will be moving out from the cytoplasm of cell to the hypotonic solution outside. Thus the concentration gradient formed will lead to the exosmosis and due to the lack of water the cell will undergo dehydration. Due to dehydration the cell will shrink in size and may undergo plasmolysis.

In case of hypertonic solution :-

Hypotonic solution is a type of solution that has a lower osmolarity as compared to the cytoplasm of the cell. This means if a cell is placed in a hypotonic solution then endosmosis occurs. Thus the water will travel inside the cell from the the hypotonic solution. This will result in the turgidity of the cell and the cell will become swollen, if the the cell becomes completely turgid further endosmosis will lead to bursting of the cell membrane.

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