Page 223 - New Medley 4 Semester 1

Let us see that sunlight is necessary for photosynthesis.

• Take a potted plant which was kept in a dark room for
one day.
• Now, cover a part of one of its leaves with a strip of black
paper.
• Keep this potted plant in sunlight for a few hours.

• Pluck the covered leaf and remove the black paper strip.
• Boil this leaf in water for five minutes and then boil it in
alcohol on a water bath.
• Wash the leaf in cold water.

• Now, put a few drops of iodine solution on this leaf and
see what happens.

The whole leaf turns blue-black, but
the part which was covered with
black paper remains the same. Why does it
happen so?

This happens because the
part of leaf which was
covered with black paper,
did not get sunlight and
hence, could not make
food. This shows that plants
can make food only in the
presence of sunlight.

Teacher wants students to know some unusual plants which do not have

leaves or do not have chlorophyll.

Let us know about some
special type of plants. How does cactus plant
Plants like cactus do make its food, if it does
not have leaves. not have leaves?

Look at the cactus
plant. Its stem is green
because it contains
chlorophyll. Thus, its
green stem makes the
food just like leaves.

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