Page 128 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six
P. 128
Biology for Secondary Schools
Materials: Potted plant, manila 6. Test the detached leaf for starch
card, paper clips, absolute ethanol using the standard procedure.
or methylated spirit, iodine solution, What do you notice?
test tube, beaker, water, white tile, 7. Discuss your observations with
notebook, and pen or pencil your classmate.
FOR ONLINE READING ONLY
Procedure General conclusion
1. Place the potted plant in a dark The above experiments have shown
place for 24 hours to destarch its that chlorophyll, water, carbon
leaves. dioxide, and sunlight are necessary
2. Use manila card (opaque paper) for photosynthesis. The process of
and paper clips to cover the upper photosynthesis cannot take place in the
and lower epidermis of one leaf absence of any of these. If sunlight or
as shown in Figure 6.7. carbon dioxide are in low supply, the
rate of photosynthesis will decrease. In
addition, magnesium and iron elements
Leaf are essential for the production of
Paper clip chlorophyll. If they are in low supply,
Manila card the rate of photosynthesis decreases
because chlorophyll pigment is
insufficient.
Activity 6.7: An experiment to verify
that photosynthesis produces oxygen
Materials: Test tube, beaker, sodium
hydrogen carbonate, filter funnel,
pond weed, wooden splint, a lighter,
notebook, and pen or pencil
Figure 6.7: Leaf in a potted plant covered Procedure
with manila card
1. Put the pond weed in a beaker
3. Put the plant in bright sunlight for containing water. Put one spatula
6 hours. of sodium hydrogen carbonate in
4. Detach the leaf that has been the water. This serves as a source
covered by manila card from the of carbon dioxide.
plant. 2. Put a plant under a funnel and
5. Remove the paper clips and collect the bubbles in an inverted
manila card. test tube, as shown in Figure 6.8.
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