QS Study

Requirements: One small beaker, one test tube, a stand with clamp, mercury, some gram seeds, a piece of caustic potash and a pair of forceps.

Procedure: Partly filled up the beaker with mercury. Fill up a test tube completely with mercury and invert it with the help of the thumb and put it in the beaker containing mercury. Now keep the test tube upright by clamping with a stand in such a condition as if the mouth of the test tube remains in the mercury but not touched the bottom of the beaker. Now introduce some germinating gram seeds into the test tube with the help of a pair of forceps. As the seeds are lighter than mercury, they will float over Mercury. Leave the experimental set for observation.


Fig. The experiment of Anaerobic Respiration

Observation: After several hours it will be seen that the mercury at the top of the test tube has displaced downwards by a gas released by germinating gram seeds. Now introduce the caustic potash stick into the test tube with the help of a pair of forceps. It will be observed that the test tube is completely filled up with the displaced mercury as the gas is absorbed by caustic potash stick.

Conclusion: The gas is absorbed by caustic potash so it was CO2 and respiration of gram seeds released the gas. Air cannot be present in the mercury and the gram seeds were present in mercury. So the respiration of gram seeds was anaerobic. Therefore in anaerobic respiration O2 is not required.