28-30. Explain what is happening to these plant and animal cells that are placed in three
different concentrations of aqueous solutions. Which situation is optimal for plant cells? Why?
Solution
In all these cases,osmosis is happening.Fig 1, fig 2, and fig 3 are having hypotonic, isotonic and
hypertonic solutions respectively.
Case 1:
(i) Animal Cell - The figure shows that animal cell burst. This happens due to the fact that
concentration of solute is lesser outside the cell and higher inside the cell. Due to this the solvent
moves inside the cell. As a result cell swells up and eventually bursts.
(ii) Plant Cell - The figure shows that plant cell has swollen up in size.The reason of swelling up
remains the same as above. But the presence of cell wall and large central vacuole do not let
plant cell burst easily.
Case 2:
(i) Animal Cell - The figure shows the cell is in its normal shape and size.This is the case when
the concentration of solute inside and outside of the cell remains the same. Due to which the
amount of solvent molecules moving inside the cell is equal to the amount of solvent moving
outside the cell and hence the shape of the cell is maintained.
(ii) Plant Cell - Being the same case of isotonicity, the reason remains the same as above.
Case 3-
(i) Animal Cell - The figure shows that cell shrinks from the original size.The reason being that
the concentration of solute is higher outside and lesser inside the cell. As a result the solvent
molecules move from inside to outside the cell.Hnce, the cell shrinks.
(ii) Plant Cell- The situation and the reason is same as above.
Hypotonic environment is optimal for plant cells.Hypotonicity will help plant cell to take up
more water inside the cell and they will swell up and become turgid.The plant cell should be
turgid to because it helps plant cell to maintain stability and rigidity of plant tissues.
different concentrations of aqueous solutions. Which situation is optimal for plant cells? Why?
Solution
In all these cases,osmosis is happening.Fig 1, fig 2, and fig 3 are having hypotonic, isotonic and
hypertonic solutions respectively.
Case 1:
(i) Animal Cell - The figure shows that animal cell burst. This happens due to the fact that
concentration of solute is lesser outside the cell and higher inside the cell. Due to this the solvent
moves inside the cell. As a result cell swells up and eventually bursts.
(ii) Plant Cell - The figure shows that plant cell has swollen up in size.The reason of swelling up
remains the same as above. But the presence of cell wall and large central vacuole do not let
plant cell burst easily.
Case 2:
(i) Animal Cell - The figure shows the cell is in its normal shape and size.This is the case when
the concentration of solute inside and outside of the cell remains the same. Due to which the
amount of solvent molecules moving inside the cell is equal to the amount of solvent moving
outside the cell and hence the shape of the cell is maintained.
(ii) Plant Cell - Being the same case of isotonicity, the reason remains the same as above.
Case 3-
(i) Animal Cell - The figure shows that cell shrinks from the original size.The reason being that
the concentration of solute is higher outside and lesser inside the cell. As a result the solvent
molecules move from inside to outside the cell.Hnce, the cell shrinks.
(ii) Plant Cell- The situation and the reason is same as above.
Hypotonic environment is optimal for plant cells.Hypotonicity will help plant cell to take up
more water inside the cell and they will swell up and become turgid.The plant cell should be
turgid to because it helps plant cell to maintain stability and rigidity of plant tissues.
