Page 126 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

4. Remove the leaf from the
absolute ethanol and rinse it in
Beaker warm water. The water softens

Water the leaf.
FOR ONLINE READING ONLY
Leaf 5. Put the leaf on a white tile. Add
Wire gauze 2-3 drops of iodine solution on
Flame the leaf. What do you observe?
Tripod stand 6. Record your observations.
Gas pipe
Bunsen burner
Note: The blue-black colour indicates
the presence of starch.
Figure 6.3: Boiling a leaf to kill the cells

3. Put the boiled leaf in the test Activity 6.4: An experiment to
tube containing absolute ethanol. determine the importance of carbon
Cover the test tube with cotton dioxide in photosynthesis
wool. Place the test tube in a
beaker of boiling water, as shown Materials: Conical flasks, thread,

in Figure 6.4. The absolute corks, soda lime, water, iodine solution,
dropper, potted plant, notebook,
ethanol dissolves the chlorophyll. absolute ethanol, white tile, test tube,

Caution source of heat, beaker, pen or pencil
Do not heat absolute ethanol directly
because it is highly flammable. Cover Procedure
the test tube with cotton wool. 1. Place the potted plant in dark
place for at least 24 hours to
destarch its leaves.
Test tube
Beaker 2. Enclose a leaf (A) in a conical
Methylated spirit flask containing soda lime, as
Water
Leaf shown in Figure 6.5. This leaf
Wire gauze will not have a supply of carbon
Flame
Tripod stand dioxide from the air because soda
Gas pipe lime absorbs carbon dioxide.
Bunsen burner 3. Enclose a second leaf (B) in a

conical flask containing some
Figure 6.4: Decolourising a leaf by using water.
absolute ethanol

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