Page 4 - ACTIVE SCIENCE 4 TOC

energy of the sun. The sugar is stored in the form of starch in the leaf for its own
use and for animals.

The carbon dioxide is taken in through the stomata. The water is absorbed from

soil through the roots and carried to the plant parts by the stem. The process of
photosynthesis can be shown as:
Light
Carbon Dioxide + Water Sugar + Oxygen
Chlorophyll

Activity 1.1

Aim : To test a leaf for the presence of starch as food.

Materials Required : • a burner/tripod stand/wire gauze • a beaker

• boiling tube • tongs
• test tube holder • white tile
• leaf to be tested (hibiscus leaves are excellent)

• 90% ethanol • iodine solution

Procedure : 1. Take a green leaf from a plant that has been exposed to
sunlight for a few hours.

2. Half-fill a beaker with
water. Heat the water
until it boils. Maintain

the water at the boiling
point.

3. Use tongs to place the
leaf in the boiling water.
Boil for 2 minutes.

4. Turn off the burner.

5. Place the boiled leaf in a
boiling tube containing

90% ethanol.

6. Place the boiling tube in hot water and boil for 10 minutes or
until the leaf decolourises.

7. Gently remove the leaf from the test tube and wash with a fine
drip of cold tap water.

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Active Science-4