Page 73 - EM BIOLOGY NOTES 10TH CLASS PSR DIGITAL BOOKS

LAB ACTIVITIES
1. TEST THE PRESENCE OF STARCH IN LEAVES 2. CO IS ESSENTIAL FOR PHOTOSYNTHESIS

AIM AIM 2
To test the presence of starch in leaves.
APPARATUS To prove that CO is essential for photosynthesis.
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1. Beaker 2. Test tube 3. Water original preparation APPARATUS
4. Methylated spirit (Ethanol) 5. Tripod stand lab activity 1. Potted plant 2. Wide mouthed glass bottle 3. KOH solution
pl. scan QR
6. Asbetos gauze 7. Bunsen burner 8. Petridish 4. Split cork 5. Iodine solution 6. Grease
9. Iodine solution 10. Leaf 11. Dropper
DIAGRAM
RAJU’S NATURAL SCIENCE ACADEMY
DIAGRAM

PROCEDURE
PROCEDURE 1. Take a potted plant with long and narrow leaves.
1. Take a leaf of potted plant. 2. Keep it into dark room for a week days. (due to this, leaves are free from starch)
2. Boil the leaf in methylated spirt over a water bath. 3. Take a glass bottle. 4. Take 5-6 ml of KOH solution into the bottle.
(if we boil the leaf in methylated spirit directly on bunsen burner, spirit will burn) (it absorbs the CO which is present in the bottle)
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3. Till leaf becomes pale white. 5. Insert half of the leaf into the bottle.
(chlorophyll dissolved in the methylated spirit leaf become pale white) 6. Close the bottle with split cork and grease.
4. Spread the leaf in a petridish. (it prevents the entering of CO into the bottle)
5. Add a few drops of iodine on it. 7. Keep the entire setup in sunlight for 4-5 hours.
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OBSERVATION
1. Leaf turns into bue-black colour. 8. Detach the leaf from the plant. 9. Test the leaf by iodine solution.
2. It indicates that the leaf contains starch. OBSERVATION
INFERENCE 1. Part of the leaf outside the bottle turns into blue-black colour.
This experiment proves that leaf contains starch. 2. Part of the leaf inside the bottle does not turns blue-black colour.
PRECAUTIONS INFERENCE : This experiment proves that CO is essential for photysynthesis.
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1. We should boil the leaf in methylated spririt over a water bath carefully. PRECAUTIONS 1. Before inserting the leaf we should take KOH solution into the bottle.
2. We should boil the leaf till it will become pale white. 2. We should close the bottle without leaving any gap.

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