WELCOME TO
our
PRESENTATION

TOPIC NAME:
OSMOSIS & DIFFUSION
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Group - 6 (Blue birds)
Ourselves
• Md. Aminul Haque - 15309039
• Md. Mahmud Hasan - 15309010
• Mahabub Rahman Sajib - 16209018
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OSMOSIS and DIFFUSION
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Molecules are always moving
Molecules move randomly and bump into
each other and other barriers
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Movement of molecules from higher
concentration to lower concentration slowly
spread apart over time. This is diffusion.
T1
T2 T3
Diffusion
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Diffusion
• Movement of molecules from an area of high
concentration to an area of lower concentration.
• Factors that affect the rate of diffusion: size of
molecules, size of pores in membrane, temperature,
pressure, and concentration.
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Diffusion
[High] [Low]
concentrated, high energy molecules
diffuse, low energy molecules
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Diffusion will continue until equilibrium is reached. This
means there will be an equal distribution of molecules
throughout the space. This is why food coloring moves
throughout a beaker of water; why odors smell strong at
first and then disappear over time.
Equilibrium, a result of diffusion, shows the uniform distribution of
molecules of different substances over time as indicated in the
above diagram.
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Significances of Diffusion
• It is an essential process in exchange of
gases during respiration and
photosynthesis.
• Uptake of minerals is also affected by the
process of diffusion.
• It helps in removal of excess water by the
process of transpiration.
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Osmosis
• Osmosis is the movement of water through a
semi-permeable membrane
• At first the concentration of solute is very high
on the left.
• But over time, the water moves across the semi-
permeable membrane and dilutes the particles.
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Osmosis – A Special kind of Diffusion
Diffusion of water across a selectively permeable membrane (a
barrier that allows some substances to pass but not others).
The cell membrane is such a barrier.
Small molecules pass through – ex: water
Large molecules can’t pass through – ex: proteins and complex
carbohydrates
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Hypotonic – The solution on one side of a membrane where the solute concentration
is less than on the other side. Hypotonic Solutions contain a low concentration of
solute relative to another solution.
Hypertonic – The solution on one side of a membrane where the solute concentration
is greater than on the other side. Hypertonic Solutions contain a high concentration
of solute relative to another solution.
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Over time molecules will move across the
membrane until the concentration of solutes
is equal on both sides. This type of solution
is called isotonic .
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Turgor Pressure builds in the cell
and causes osmosis to stop
because of the rigid cell wall.
Plants will wilt when cells
lose water through osmosis.
Hypotonic
Solution
Hypertonic
Solution
PLANT CELLS
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ELODEA CELLS
As viewed under the microscope
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Significances of osmosis
 It is an essential step in the exchange of
gases during respiration and
photosynthesis.
 During passive Salt uptake, the irons are
absorbed by simple process of diffusion.
 Last step in stomata transpiration is the
diffusion of water vapors from the
intercellular spaces into the outer
atmosphere through open stomata.
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PASSIVE TRANSPORT
Passive transport occurs without expenditure of energy. Molecules
move using their own kinetic energy . Diffusion and osmosis are
examples of passive transport. Passive transport allows cells to get
water, oxygen and other small molecules that they need. It also
allows the cell to get rid of waste such as carbon dioxide.
DIFFUSION
OSMOSIS
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THE END
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