Question

An experiment was set up as shown in the figure given below . The twig in the diagram was intact on the plant and it was as such in sunlight for a few hours .

(i) What is the aim of the above experiment ? 
(ii) Why was potassium hydroxide placed inside the conical flask ?
(iii) What test would you perform on the leaf inside the flask?
(iv) What is the expected result of the above test ?
(v) Is it necessary to similarly test on outer leaf also ? Giva a reason .

Answer 1

(i) The aim of the experiment is to prove that CO₂ is necessary for photosynthesis.
(ii) Potassium hydroxide absorbs CO₂ from the surrounding. It is placed to remove CO₂ within the conical flask.
(iii) The leaf inside the conical flask would be tested for the presence of starch by the application of iodine.
(iv) The expected result of the above test is - No change in the colour will be observed.
(v) Yes, it is necessary to similarly test on the outer leaf also to show that leaves present in CO₂ show photosynthesis.