Na-e
Date
Normal and
Plasmolyzed Cells
Dilfusion of water moleculesacrossa cell's outer membranefrom
areas of high water concentration to areas of low water
concenlratlon is called osmosis.This movement of water may be
harmful to cells. If too much water is lost from the cell, the cell
membrane and the cell contents shrink away from the cell wall.
This is called plasmolysis.Plasmolysismay lead to death of the
cell. Most cells live in an environment where movement ol water in
and out of the cell is about equal. Therefore, there are no harmful
effects to the cell.
OBJECTIVES
. Prepare a wet mount ol an Elodealeaf.
. Observe plasmolysis In the cell as salt solution is
added to the wet mount.
. Observethe reversalof plasmolysisas the salt
solution is dilutedr Compareand'diagramnormal cells in tap water
with plasmolyzedcells ln salt solution.
MATERIALS
microscope
microscope slide
paper towel
coverslip
forceps
Elodea (water plant)
droppers (2)
tap water
6 % " s a l ts o l u t i o n
PROCEDURE
l. Prepare a wet mount ol a.n Elodealeaf as
follows. Use Figure I as a guide.
2. Use a dropper to place one or two drops of tap
water on a microscopeslide.
3. Place one leaf, taken from the top whorl of
leaves on a sprig ol Elodea,in the drop of
water. Cover the leaf with a coverslip.
4. Observe the leaf under both low and high
porv'/ers.
Note the location of chloroplastsin
relation to the cell wall.
5, Diagram a normal cell in the spaceprovided in
Data and Observations.Labelthe cell wall. cell
membrane, and chloroplasts.
6. Use a clean dropper to add a Aroi of 6% salt
solution along one edge of the coverslip.Place
a piece of paper towel along the oppositeedge
of the coverslip. The tap water will soak lnto
the paper towel, drawing the salt solution
under the coverslip.
7. Observe the leaf under both low and high
powers. Again note the locationof the
1 to 2 drops
tap water
Elodea
leal
Figure l.
chloroplasts in relation to the cell wall. ll the
cell membrane and the cell contents have
shrunk away from the cell wall, the cell has
plasmolyzed.
8 . Diagram a plasmolyzed cell in the space
p r o v i d e d i n D a t a a n d O b s e r v a t i o n s .L a b e l t h e
c e l l w a l l , c e l l m e m b r a n e ,a n d c h l o r o p l a s t s .
9. Add a drop of tap water to the wet mount,
followingthe procedure in step 6. Observe the
a p p e a r a n c eo l t h e c e l l s .
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DATA AND OBSERVATIONS
Normal cell
Plasmolyzed cell
ANALYSIS
l. Describethe location of chloroplasts in a normal Elodeacell (in tap water)'
2. DesCribethe location of chtoroplasts in a plasmolyzedcell (in salt solution)'
3. What did you observewhen salt solution was addedto the wet mount?
4 , In which direction did water move when salt solution was added?
b.
What did you observe when tap water diluted the salt solution?
6 . In which direction did water move when tap water diluted the salt solutlon?
t.
Describethe process of PlasmolYsis.
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