Question

Q7. Study the following activity to test a leaf for presence of starch and answer the questions that follow,
ACTIVITY (Experimental investigation): To test a leat for starch
Pluck a leaf from a plant which has been exposed to
sunlight. Boil it for about five minutes in water to
softer it. Place it in a test tube containing alcohol
Place the test tube in a beaker of water and warm
the water gently until the alcohol begins to boil.
(Caution: Do not allow the water in the beaker to
boil) The alcohol will dissolve the chlorophyll and
the leaf will lose its green colour (Fig. 1.2).
Wash the leaf in warm water to remove the alcohol.
Now spread the leaf out flat on a white tile and pour
lodine solution on it. Remove the leaf from the iodine
and wash it with water. Hold it up against the light.
You will observe that parts of the leaf become
a 1.2 Testing a lot to starch
blue-black. These parts of the leaf have starch in them.
a. What is the purpose of softening the leaf by boiling in water?
b. What change will be observed in the colour of alcohol?
c. Why is the test tube containing the leaf not heated directly?​

Answer 1

Answer:

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