Osmosis: is the movement of water from a high concentration to a low concentration through a partially permeable membrane. It is a special type of diffusion Osmosis: is a process in which a fluid passes through a semipermeable membrane, moving from an area in which a solute such as salt is present in low concentrations to an area in which the solute is present in high concentrations.

1. WELCOME TO MY
PRESENTATION
My topic is :osmosis
30 March
2018
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2. Osmosis
Osmosis: is the movement of water from a high
concentration to a low concentration through a partially
permeable membrane. It is a special type of diffusion
Osmosis: is a process in which a fluid passes through a
semipermeable membrane, moving from an area in which
a solute such as salt is present in low concentrations to an
area in which the solute is present in high concentrations.
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3. Types of osmosis
 Reverse osmosis: is a separation process using pressure
to force a solvent to pass through a semi permeable
membrane that keeps the solute on one side and directs
the pure solvent to the other side.
 Forward osmosis: uses osmosis to directly separate
water from a feed solution with unwanted solutes
A draw solution uses the feed solution to force water
through a semi permeable membrane
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4. Example of osmosis
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5. Osmosis vs Diffusion
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6. Some characteristic of osmosis
Osmosis occurs only in liquids.
Osmosis requires semi-permeable membrane.
In this process movement of solvent takes place from lower
concentration to high concentration through semi-permeable
membrane.
Osmosis all time requires water.
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7. Why osmosis is important?
Osmosis helps in absorption of water by plants.
Movement of water from one cell to another is due to osmosis.
Opening and closing of stomata is brought about by osmosis.
Due o osmosis the turgidity of the cells and hence the shape.
They gain water by osmosis through their roots.
Conduction of water from xylem elements to the neighboring
cells is controlled by osmosis 30 March 2018 7

8. Osmotic Conditions
• There are three types of osmotic conditions that affect
living cells and they are called hypertonic, hypotonic,
and isotonic states. These terms describe the osmotic
state of the solution that surrounds a cell, not the
solution inside the cell.
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9. Cont
1. Hypertonic solution : the concentration of the cell is less than outside
of the cell. Water moves out of the cell to try to even out the
concentration.
2. Hypotonic solution: the cell has higher concentration in it than in the
area surrounding it. Water moves in to the cell to equal out the
concentration.
3. isotonic solution: the cell has equal proportion of concentration with
the area surrounding. Water continually flows in and out to keep
concentration even. 30 March 2018 9

10. Isotonic Solution
• Isotonic solutions: the concentration of
solute inside and outside of the cell is
the same.
• Isotonic:
• Water in = Water out
• No net movement of water.
• Molecules in equilibrium.
• Normal state for animal cells.
• Cell in homeostasis.
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11. Hypotonic solution
Hypotonic:
• Water enters cell.
• Cell swells and bursts
(cytolysis).
• Give plant cells shape and
support.
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12. Hypertonic solution
Hypertonic:
•Water exits cell.
•Cell shrinks
(plasmolysis) due
to water loss. 30 March 2018 12

13. Factors Affecting the Rate of Osmosis
Temperature: The higher the temperature, the faster the movement of
water molecules across the semi permeable membrane.
Surface Area: The larger the surface area, the more space for the
molecules to move easily across the smaller the area, the more
restricted the movements of the molecules and the slower the
movement.
Light and dark :They are also factors of osmosis; since the brighter the
light, the faster osmosis takes place.
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14. Cont
Difference in Water Potential :The higher the difference in water
potential, the faster the osmosis for the lesser water molecules are in
the region of low concentration, more water molecules from the region
of higher concentration can enter faster and easier.
Concentration gradient : The movement of osmosis is affected by the
concentration gradient; the lower the concentration of the solute within
a solvent, the faster osmosis will occur in that solvent.
Pressure :The more the pressure, the faster the molecules will move
for they are being pushed faster across a low concentration.
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15. Osmotic Pressure
Osmotic pressure: is the pressure which is applied to a solution to prevent
the inward flow of water across a semi permeable membrane, or simply
put it is the pressure required to stop osmosis
Osmotic pressure is shown when water molecules that attempt to cross the
semi permeable membrane are prevented from doing so.
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16. Osmotic Gradient
The osmotic gradient is the difference between two concentration
solutions at either side of a semi permeable membrane that
distinguishes the different percentage of a specific particle
concentration that is dissolved in a solution.
 The osmotic gradient acts on solutions having a semi permeable
membrane between them allowing water to diffuse between the
two solutions toward the solution with the higher concentration.
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