Lab Report Diffusion and Osmosis
Lab Report Diffusion and Osmosis
I.
I. TitleTitle = = Diffusion Diffusion and and OsmosisOsmosis
II.
II. InIntroductiotroductionn ==
Plasmolysis Plasmolysis
Plasmolysis is the process in plant cells where the cytoplasm pulls away from the cell wall due to the loss Plasmolysis is the process in plant cells where the cytoplasm pulls away from the cell wall due to the loss of water through osmosis
of water through osmosis..The reverse process,cytolysis, can occur if the cell is in a hypotonic solutionThe reverse process,cytolysis, can occur if the cell is in a hypotonic solution
resulting in a higher external osmotic pressure and a net flow of water into the cell
resulting in a higher external osmotic pressure and a net flow of water into the cell.. Through observationThrough observation
of plasmolysis and deplasmolysis it is possible to determine the tonicity of the cell's environment as well of plasmolysis and deplasmolysis it is possible to determine the tonicity of the cell's environment as well as the rate solute molecules cross the cellular membrane
as the rate solute molecules cross the cellular membrane..
Diffusion Diffusion
Molecules are in constant motion and tend to move from regions where they are in higher concentration Molecules are in constant motion and tend to move from regions where they are in higher concentration to regions where they are less concentrated
to regions where they are less concentrated..Diffusion is the net movement of molecules downDiffusion is the net movement of molecules down
their concentration gradient
their concentration gradient.. Diffusion can occur in gases, in liquids, or through solidsDiffusion can occur in gases, in liquids, or through solids..An example of An example of
diffusion in gases occurs when a bottle of perfume is opened at the front of a room
diffusion in gases occurs when a bottle of perfume is opened at the front of a room..Within minutesWithin minutes
people further and further from the source can smell the perfume people further and further from the source can smell the perfume..
Osmosis Osmosis
Osmosis is a specialized case of diffusion that involves the passive transport of water
Osmosis is a specialized case of diffusion that involves the passive transport of water .. IInosmosis water nosmosis water
moves through a selectively permeable membrane from a region of its higher concentration to a region of moves through a selectively permeable membrane from a region of its higher concentration to a region of its lower concentration
its lower concentration.. The membrane selectively allows passage of certain types of molecules whileThe membrane selectively allows passage of certain types of molecules while
restricting the movement of others restricting the movement of others..
Hypertonicity Hypertonicity
A hypertonic solution is a solution having a greater effective osmole concentration than the cytosol A hypertonic solution is a solution having a greater effective osmole concentration than the cytosol.. IItt
contains a greater concentration of impermeable solutes on the external side of the membrane
contains a greater concentration of impermeable solutes on the external side of the membrane..When aWhen a
cell¶s cytoplasm is bathed in a hypertonic solution, water will be drawn into the solution and out of the cell¶s cytoplasm is bathed in a hypertonic solution, water will be drawn into the solution and out of the cell by osmosis
cell by osmosis.. IIf water molecules continue to diffuse out of the cell, it will cause the cell to shrink, or f water molecules continue to diffuse out of the cell, it will cause the cell to shrink, or
crenate
crenate.. A hypertonic solution is used in osmotherapy[1] to treat cerebral hemorrhageA hypertonic solution is used in osmotherapy[1] to treat cerebral hemorrhage..
Hypotonicity Hypotonicity
A hypotonic solution is a solution having a lower effective osmole concentration than the cytosol A hypotonic solution is a solution having a lower effective osmole concentration than the cytosol.. IItt
contains a lesser concentration of impermeable solutes on the external side of the membrane
contains a lesser concentration of impermeable solutes on the external side of the membrane..When aWhen a
cell¶s cytoplasm is bathed in a hypotonic solution the water will be drawn out of the solution and into the cell¶s cytoplasm is bathed in a hypotonic solution the water will be drawn out of the solution and into the cell by osmosis
cell by osmosis.. IIf water molecules continue to diffuse into the cell, it will cause the cell to swell, up tof water molecules continue to diffuse into the cell, it will cause the cell to swell, up to
the point that cytolysis (rupture) may occur
the point that cytolysis (rupture) may occur .. IIn plant cells, the cell will not always rupturen plant cells, the cell will not always rupture..When placedWhen placed
in a hypotonic solution, the cell will have Turgor Pressure and proceed with its normal functions in a hypotonic solution, the cell will have Turgor Pressure and proceed with its normal functions..
Isotonicity
A condition or property of a solution in which its effective osmole concentration is the same as the solute concentration of another solution with which it is compared. It is a concentration of both water and total
solute molecules are the same in an external solution as in the cell content . Water molecules diffuse
through the plasma membrane in both direction.The rate of water diffusion is the same in both direction
that cell will neither gain nor lose water .
III. Goal =
y To observe about osmosis and diffusion process
y Differentiate between hypertonic, hypotonic and isotonic y Examine the effects of osmosis on plant cells
IV. Materials/Ingredients = Experiment 1:
- A Microscope - Microscope slide - Cover slip
- A slice of Rhoeo discolor
Experiment 2: - A glass of water - A glass of NaCl 10 % - Measure balace - a potato (2 cube, 1cm x 1 cm) - a carrot (2 cube, 1cm x 1 cm) - a tuber (2 cube, 1cm x 1 cm) Experiment 3:
- Two glass of water - Pipet
- Methyl blue - Eosin
V. Methods = Experiment 1:
1. Prepare all the materials.
3. Put it on the microscope slide, add with a drops of water, cover it with cover slip, check the
structure inside the cells by microscope, draw it.
4. Dry the cells by tissues, and drop a drops of sugar %, check the structure inside the cells again,
draw it and compare it with the first draw (especially the stomata). Experiment 2:
1. Prepare all the materials.
2. Cut the potatoes, carrots, and tuber , with a cube shape in 1cm x 1cm dimension .
3. Measure the mass with measure balance, write it.
4. Prepare two glass, one is for a tap water and the other for NaCl 10%.
5. Put inside each of the potato, carrot, and tuber .
6. Wait until 15 minutes.
7. After that, re-measure it again, compare the mass. Experiment 3:
1. Prepare all the materials.
2. Prepare two glass of water, with the same amount of water .
3. Drop just one drop methyl blue in one glass, and drop eosin in the rest.
4. Watch the spread of the solute, count with the stopwatch.
5. Look and compare how much the time to spread to all part of the glass.
VI. R esult and Discussion = Experiment 1 :
Before After(add sugar)
The stomata still clearly seen. The stomata is open and broken.
Experiment 2:
Medium The object Mass before
(g)
Mass After (g) Change in mass (g) Explanation
Carrot Tuber NaCl 10% Potato Carrot Tuber Experiment 3: Difussion=
-Methyl Blue (add one drop to the 29 ml water)
Time to spread = 5 minutes 10 seconds -Eosin (add one drop to the 29 ml water)
Time to spread = 3 minutes 6 seconds
Discussion Why??
VII. Conclusion =
The factor why there is an error in our observation: - NaCl mot spread well inside the water - The measure balance not quite accurate
The factor why eosin is more faster to spread than methyl blue Movement of Molecules in Cells
VIII. R eference =
http://www. phschool.com/science/biology_place/labbench/lab1/concepts .html