How do you prove that sunlight is essential for photosynthesis? with diagram?
Answers
Answer:
Explanation:
Procedure to prove light is essential for photosynthesis:
Take the potted plant and keep it in a dark place for 2-3 days so that the leaves get destarched.
Attach light proof black paper strips on both sides of the leaf with the help of paper clips.
Place the plant in sunlight for 3-4 hours.
Explanation:
Photosynthesis is a physiological process of green plants. One of the important factor required for photosynthesis is sunlight. In this resource I have explained in detail how an experiment can be conducted to prove the importance of the factor sunlight for this process. Along with the experiment I gave some important questions as well as answers related to the experiment which will be useful for those preparing for final practical or theory exams of various Board
Introduction
Photosynthesis is an important physiological activity of green plants. For photosynthesis to occur in green plant the factors required are Sunlight, Chlorophyll and Carbon dioxide. To prove the necessity of these factors there are certain specific experiments have to be in the laboratory. So students must know clearly how a particular experiment will be done for each factor clearly and also must realize why a particular step will be done for the success of the experiment with reasons.
Aim of the experiment:-
To prove Sunlight necessary for green plants to prepare their food.
Requirements:-
A well watered potted green plant, two strips of black papers, small clips, spirit lamp or bun sen burner, test tube, beaker, Petr-dish, water, mentholated spirit or rectified spirit or ethanol, iodine solution.
Experiment for Sunlight is necessary for Photosynthesis
Sunlight is necessary for Photosynthesis experimental setup:- (Courtesy:-dev.elearn.punjab.gov.pk)
Procedure for the experiment
Before starting the experiment to prove Sunlight is necessary for photosynthesis an important step has to be carried out is known as De-starching. De-starching is a process in which the starch present in the leaves will be eliminated by keeping the plant in dark room or closed cup-board for about 48 hours. This step is done to ensure that previously manufactured food in the leaves get consumed when the plant was kept in dark place since photosynthesis doesn't occur at that time.
Next strips of black paper will be arranged one on either side of the selected leaf of the De-starched plant with the help of clips. Now the whole plant is kept in bright Sunlight for about 3-4 hours. Then the strips of black papers are removed from the experimental leaf and then starch test or Iodine test is conducted for the experimental leaf.
How to conduct starch test on the experimental leaf
By following steps Iodine test will be conducted for the experimental leaf:-
Steps to conduct Iodine Test
Steps to conduct Iodine Test:-(Courtesy:-dev.elearn.punjab.gov.pk)
First the experimental leaf is dipped in boiling water in the beaker for few minutes so that the cells of the leaf will be killed and metabolic process of the leaf cells will be stopped.
Now the boiled leaf in water is removed from the beaker with the help of a forceps and is placed in a test tube containing mentholated spirit. Then the leaf is boiled in mentholated spirit or ethanol over a water bath by keeping it in boiling water for about 10 minutes. The leaf looses its chlorophyll by boiling it in mentholated spirit and becomes pale-white.
Then the pale-white leaf is removed from the test tube and then it is washed in warm water to soften it.
Then this leaf is spread over a white porcelain tile and iodine drops are poured over at different places of the leaf.
Result of Iodine test
Iodine is a purple colored reagent used to test the presence or absence of starch in the leaf conducted for photosynthesis process. When iodine test is conducted for the experimental leaf, the leaf where black paper was covered will turn into brown color and the part of the leaf which is not covered with black paper will turn into blue-black color. This result clearly indicates starch is formed in the leaf where sunlight is available and starch is not formed where the leaf doesn't got the sunlight as it is covered by black paper.
