Getting to know plants (Part-4)

  Getting to know plants 


Q.11. Write an activity to show transpiration in leaves.
Ans. We will require a herb, two transparent polythene bags and some string. Do this activity during day time on a sunny day. Use a healthy, well watered plant that has been growing in the sun, for this activity. Enclose a leafy branch of the plant in a polythene bag and tie up its mouth as shown in Figure. Tie up the mouth of the empty polythene bag and keep it also in the sun. After a few hours, observe the inner surface of the bags.

We see that there are few droplets of water in the polythene bag enclosing a leafy branch of the plant while no drops in empty polythene bag. This is because leaves lose water in the form of water vapour and this process is known as transpiration.

                                  

Q.12. Write an activity to show that leaves contain starch.

Ans. We would require a leaf, spirit, a beaker, test tube, burner, water, a watch glass and iodine solution for this activity. Take a leaf in a test tube and pour spirit to completely immerse the leaf.

Now, place the test tube in a beaker half filled with water. Heat the beaker till all the green colour from the leaf comes out into the spirit in the test tube. Take out the leaf carefully and wash it in water. Place it on a watch glass and pour some iodine solution over it. We will see the leaf turning blue black in colour. This mean that the leaf has starch in it.

                               

Q.13. Write an activity to show leaves produce starch in the presence of sunlight?

Ans. Place a potted plant with green leaves, in a dark room for a day or two. Now, cover a portion of a leaf of the plant completely with black paper and leave the plant in the Sun for a day. Remove the leaf covered in black paper and repeat the test for starch by doing iodine test.

Uncovered part of the leaf shows the presence of starch by turning blue black in colour while covered part of the leaf does not. 

This shows that leaves produce starch in the presence of sunlight.

                      Experiment on Photosynthesis-Sunlight is necessary for Photosynthesis

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