Question

Write a simple experiment to demonstrate that chlorophyll is necessary for photosynthesis to take place.

Answer 1

Hint: Photosynthesis is the process by which plants make their food in the presence of sunlight to convert light energy into chemical energy. Oxygen is the byproduct during photosynthesis. Sunlight, water, and carbon dioxide are essential to perform photosynthesis. Photosynthesis gives us oxygen which we need to breathe and we, in turn, exhale carbon dioxide which is needed by the plant.

Complete answer:
A potted plant is taken whose leaves are partly white and green. The green leaf has chlorophyll but the white part does not contain chlorophyll. Put the plant in a completely dark place for about three days for research in its leaves. Take the potted plant from the dark place out and keep it in the sunshine for about three to four days. Take the variegated leaf and boil it for a few minutes in water.

By boiling along with alcohol the green colour chlorophyll pigment can be removed. Now the green parts of the leaf get decolourized and we get a decolourized leaf. Wash the decolourized leaves in hot water to make it soft and remove the chlorophyll which maybe sticks to it. Pour a small amount of iodine solution on the colourless leaf and observe the change in the colour of the leaf. The outer part of the leaf will originally get white and does not turn the blue-black upon adding iodine solution which shows that there is no starch present in the outer part of the leaf. From this, we can conclude that photosynthesis does not take place without chlorophyll to make starch.

Additional information: The inner part of the leaf turns blue-black on adding iodine solution which was originally green and shows that starch is present in the inner part of the leaf. Through this observation, we can conclude that photosynthesis takes place in the presence of chlorophyll to make starch. sunlight is the most important factor for photosynthesis as the rate of photosynthesis depends upon the quantity and quality of light. Chlorophyll absorbs light and gets excited and emits electrons. The production of ATP is from these emitted electrons and the solar energy gets converted into chemical energy. In the presence of red and blue lights, the rate of photosynthesis is maximum. Whereas in the presence of green light the rate is minimum as the green light gets reflected by chlorophyll molecules.

Note: The main part of the chloroplast is the grana and stroma which are the stacks of disc-shaped compartments enclosed within a membrane and the fluid surrounding the grana respectively. In the first stage of photosynthesis, energy gets captured from the sun to break down water molecules. To make one molecule of glucose during photosynthesis it takes 6 molecules of water and six molecules of carbon dioxide. Plants slow the process of photosynthesis during autumn and as a result, leaves change their colour.