The effects of hypotonic,

hypertonic and isotonic solutions

on plant and animal cells

In comparing two solutions with different solute concentrations:1.The solution with higher solute concentration is said to be hypertonic (‘hyper’:more)2.The solution with a lower solute concentration is hypotonic (‘hypo’: less)3.Solutions in which the concentration of solute are equal are said to be isotonic (‘iso’: equal)

If the concentration of solute (salt) is equal on both sides, the water will move back in forth but it won't have any result on the overall amount of water on either side."ISO" means the same

The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell.The cell will gain water and grow larger. In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from burstingIn animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.

The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction.In plant cells, the central vacuole loses water and the cells shrink, causing wilting.In animal cells, the cells also shrink.In both cases, the cell may die.This is why it is dangerous to drink sea water - its a myth that drinking sea water will cause you to go insane, but people marooned at sea will speed up dehydration (and death) by drinking sea water. This is also why "salting fields" was a common tactic during war, it would kill the crops in the field, thus causing food shortages.

Animal and plant cells in an isotonic solutions

1.An isotonic solution is a solution in which the concentration of solute is equal to that of the cytoplasm of the cell

2.Water diffuses into and out of the cell by osmosis at equal rates

3.Therefore there is no net movement of water across the plasma membrane [no net gain or net loss of water]

4.The cells retain their normal shape

Animal and plant cells in a hypotonic solutions1.Solutions which contain a higher

concentration of water than that of the cytoplasm are called hypotonic solutions

2.Hypotonic solutions contain lower concentration of solute than the cell

3.Since the concentration of water is higher outside the cell, there is net movement of water from outside of the cell into the cell by osmosis

4.The cells gains water, swells and the internal pressure increases.

The effects of hypotonic solutions on animal cells

1. When red blood cells are immersed in a hypotonic solution, water diffuses into the cells by osmosis

2. This is because the solution outside the cells is less concentrated

3. The cells start to swell4. If the solution s extremely hypotonic, that is

consists of distilled or pure water the cells may swell up and eventually burst

5. The plasma membrane of red blood cells is too thin and delicate to withstand the osmotic pressure which develops within the cells

6. This causes the plasma membrane to rupture and the contents are released to surroundings

7. This condition is called haemolysis

The effects of hypotonic solutions on plant cells

1. When plant cells are immersed in a hypotonic solution water diffuses into the large central vacoule by osmosis

2. The solution outside of the cell is less concentrated than the inside of the cell

3. The large central vacoule expands, causing the cell to swell

4. In this condition, the cell is said to be turgid and firm as a result of the net flow of water into the cell

5. The plant cell does not burst because the rigid cell wall is strong enough to resist the increasing pressure within

6. The swelling plant cell in a hypotonic creates turgor pressure within the cell. This pressure prevents the cell from taking too much water and bursting as an animal cell would

7. Turgor pressure is very important to plant cells as it supports and maintains the shape of the cells

Animal and plant cells in a hypertonic solutions

1.Hypertonic solutions contain a higher concentration of solute than that of the cell

2.Since the concentration of water is higher within the cell, there is a net movement of water from the inside to the outside of the cell. As a result water leaves the cell.

3.This causes the cell to shrink or shrivel as its internal pressure

The effects of hypertonic solutions on plant cells

1. When plant cells are immersed in a hypertonic solution, water diffuses out of the large central vacoule by osmosis

2. Both the vacoule and cytoplasm lose water to the surroundings and shrink. The plasma membrane pulls away from the cell wall

3. This phenomenon is called plasmolysis, a shrinking of the cytoplasm due to osmosis

4. The plant cell becomes flaccid and less turgid5. The flaccidity of plant cells leads to wilting in plants6. If plasmolysis persists, death of plant cells may result7. However a plasmolyed plant cell can become turgid

again by immersing the cell in a hypotonic solution like pure water. Water is taken up by osmosis and the cells become turgid again

8. The cell is said to have undergone deplasmolysis.

The shape of Elodea cells after being placed in an hypertonic salt solution

These Elodea cells were placed in a 10% NaCl solution. The

contents of the cells was reduced but the cell walls remained intact. Compare

these cells to normal cells in the photograph below. 

Normal Elodea cells X 400

The effects of hypertonic solutions on animal cells

1.When red blood cells are immersed in a hypertonic solution, water diffuses out of the cell by osmosis

2.The solution outside the cell is more concentrated

3.The cells lose water to the external environment, shrivel and the plasma membrane crinkles up.

4.The red blood cells are said to have undergone crenation.

CONCLUSION Effect of different solutions on blood cells

Water leaves, the cell

shrinks and crenates

No net movement of water, the cell

retains its normal size

Water enters, the cell swells

and may eventually

burst (lysis )

CONCLUSION Effect of different solutions on plant cells

Water leaves, the cytoplsm shrinks and

the cell plasmolyses

No net movement of water, the cell

retains its normal size

Water enters, the cell’s

vacuole swells and the cell

becomes turgid

CONCLUSION

The effects of isotonic, hypertonic and hypotonic

solutions on the stems of non-woody plants

animal cells

Experiment : Determining the concentration of an external

solution which is isotonic to the cell sap of plant cell

Problem statementWhat is the concentration of external solution

1. Six petri dishes are prepared and labelled A, B, C, D, E, F and G

2. Each beaker is filled with the following solutions :

Petri dish A : Distilled water Petri dish B : 0.1 M sucrose solution Petri dish C : 0.2 M Petri dish D : 0.3 M Petri dish E : 0.4 Petri dish F : 0.53. A medium-sized cork borer is pushed through a

large potato4. The potat0 tissue is removed from the cork borer5. It is then cut into a cylindicral strip 50 mm length6. Step 3 to 5 are repeated to prepare another six

cylindrical strip 7. Each strip is wipe dry with a piece of tissue paper.

8. The mass of each potato strip is weigh and recorded9. Each strip of potato is then placed in an petri dish

Result:Solutio

nPetri dish

Initial

mass (g)

Final mass (g)

Difference

in mass (g)

Percentage in mass (%)

Texture and appearance

DistilledWater A 1.4 1.8 0.4

0.4/1.4X100=28.6

FIRM

0.1MSucrosesolution

B

0.1MSucrosesolution

C

0.1MSucrosesolution

D

0.1MSucrosesolution

E

0.1MSucrosesolution

F

0.1MSucroseSolution G

GRAPH :

DISCUSSION :

1. The solution in Petri dish ___ to _____ are _______ or less concentrated than the cell sap of the strips of potato. Water diffuse into the cells by osmosis. This cause the mass of the strips of potato to increase and the potato strips to become _______ and turgid.

2. The point where the graph cuts the x-axis indicates that there _________ in the percentage of the mass of the potato strip. This means that the concentration of sucrose solution ______ at this point is _______ to the cell sap of the plant tissue.

3. The solution in petri dish ____ and ___ _ are ______ or more concentrated than the cell sap of potato tissue. Water leaves the cell by osmosis . This cause the potato strips to become ________and the mass of the strips of potato to ________.

http://www.college-cram.com/study/biology/cell-membranes/osmosis-in-a-plant-cell/

CONCLUSION

Based on the graph , the concentration of the cell sap of potato tissue is __________