Page 273 - New Medley 4 Semester 1

STEM ACTIVITY 1

Testing the presence of starch in a leaf
¶ Take a green leaf and boil it in water.
¶ Take some alcohol in a test tube and dip the boiled leaf in alcohol. Put the test tube in a beaker full of water and boil.
¶ After boiling, the leaf loses its green colour and turns colourless.
¶ Take out the leaf and wash it with cold water.
¶ Place the leaf in a watch glass and put a few drops of iodine solution on it.
¶ The leaf turns blue-black in colour.
¶ This shows that starch is present in the leaf.

STEM ACTIVITY 2

Preparing curd from milk

¶ Take some lukewarm milk in a bowl.
¶ Add one teaspoonful of curd to the milk.
¶ Mix gently with a spoon.
¶ Cover the bowl.

¶ Leave it undisturbed for 5–6 hours.
¶ Check after a few hours.
¶ Milk changes into curd with the help of curd that was mixed
with it.

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