Principle: Carbon dioxide can be tested by introducing potassium hydroxide into the test tube, which will float up through the mercury and on coming in contact with gas, will absorb the carbon dioxide and level of mercury will again rise. Materials required: Mercury Beakers Test tubes Pea seeds Inference: The seeds respire carbon dioxide gas. Precaution: The mercury should be handling carefully as it is dangerous. Experimental Setup for Anaerobic Respiration Procedure: Take eight to ten soaked and peeled off peas. Push them into the mouth of a test tube filled with mercury. Invert the test tube filled with mercury in a beaker of mercury. As a control we will take the same experiment set up with boiled seeds and sterilized with antiseptic. Observation: The seeds will float to the top and will be completely surrounded by mercury. After two days, the level of mercury in the test tube will fall. The liberated gas will be found to be carbon dioxide. In the control experiment, no gas will be liberated. Aim: An experiment to demonstrate transpiration in green plants. Principles: There is no moisture in air. Green plant s take transpiration Material s required: Bell jar Potted plant Seeds/wooden stick Cobalt chloride paper Procedures: Step A We took well watered potted plant with leaves. Enclosed the pot completely within a polythene bag and tied the mouth of the bag firmly around the base of the stem. It was done to prevent the escape of water vapor. Covered the entire plant under the bell jar. Step B Arranged another similar plant. Covered it with a bell jar exactly in the same as the first one, except we had also kept a piece of dry cobalt chloride paper by the side of the plant inside the bell jar. The paper was pasted to a wooden stick. Experimental set up for transpiration in green plants. Step C We took third bell jar without plant but with cobalt chloride paper. We kept all the bell jars together in the sun. Observation: After a day we observed: ◦ The first bell jar (A) showed water droplets condensing on its inner walls. ◦ The second bell jar (B) showed a similar condensation of water droplets at the same time, the initially blue cobalt chloride paper turned into pink. ◦ The blue colour of the cobalt paper in the third bell jar (C) did not change and there was no water droplets condensed on walls. Inference The third bell jar (C) proves that there is no moisture in the air. Condensation of water droplets and change of colour in cobalt chloride paper form blue to pink proves of transpiration in green plants. Precaution: All bell jars should be made air tight by applying grease; otherwise air from out side will get inside. All potted plants should be covered by polythene bag and sure the water vapour from pots does not escape.