Aim of the experimentGerminating seeds evolve carbon dioxide during their respiration.
Materials requiredGerminating gram seeds, freshly prepared Potassium hydroxide (KOH) solution, Petroleum jelly or wax, conical flask (500 ml), beaker (250 ml.), rubber cork with a hole, clean delivery tube bent twice at right angles, a small test tube, a piece of thread, marker and a measuring scale.
TheoryRespiration is a process by which food is oxidized by living cells of the organism to release energy for its life processes. Germinating seeds require a lot of energy during the germination process of the embryo. During that time they respire much faster and so they release more carbon dioxide.
Procedure of the experiment
Germinating seeds evolve carbon dioxide during their respiration (Image by the author)
Result of the experiment We notice there is an increase in the final water level in the glass tube after the experiment. During the experiment, the moist germinating seeds absorbed oxygen present in the conical flask and evolved carbon dioxide during the respiration of seeds. The carbon dioxide is then absorbed by the KOH solution kept inside the flask. Due to this a low pressure or vacuum is created in the flask which allowed a rise in the water level of the bent glass tube. Thus, we can prove carbon dioxide is evolved during the respiration of germinating seeds.
Here is another biological experiment "How to prepare a temporary mount of a leaf peel to show stomata?".
Questions based on the experiment from various Boards
Ans. The germinating seeds when become dry cannot respire and give out carbon dioxide. So to keep the germinating seeds moist wet cotton wool used in the flask.
Ans. Freshly prepared KOH solution may not be kept in the conical flask/The apparatus may not be made airtight/The germinating seeds may become dry.
Ans.The germinating seeds carrying out aerobic respiration. Aerobic respiration is the type of respiration in which food molecules are oxidized by using oxygen to release energy to carry life activities.
Ans. C6H12O6 + 6O2 --------------> 6CO2 + 12H2O +38 ATP + heat energy
Ans. KOH solution in the flask will absorb the carbon dioxide evolved by germinating seeds during their respiration by consuming oxygen present in the air of flask. Due to this a low pressure or vacuum is created in the flask which makes the water to rise in the delivery tube from its initial level.