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Introduction
Respiration is a catabolic process where the food is oxidised to release energy for different life processes. There are two types of respiration, namely aerobic respiration, which occurs in the presence of oxygen, and anaerobic respiration, which occurs in the absence of oxygen. The breakdown of food in the form of glucose leads to the release of energy in the form of adenosine triphosphate (ATP) and by-products like carbon dioxide and water. In this experiment, we will investigate the liberation of carbon dioxide gas during aerobic respiration.
Procedure
The procedure to conduct this experiment is as follows:
- Some germinating seeds are taken in a conical flask.
- Next, we need to take the KOH solution or pellets in a test tube, hang it in the conical flask using a thread, and close the mouth of the conical tube using a cork.
- Put one end of the delivery tube into the cork of the conical flask and another end into a water-filled beaker. The water will rise in the delivery tube due to capillary action.
- Note down the level of water reading as the initial level.
- Now, using a spatula, apply a thin smear of petroleum jelly to the junctions of the apparatus to prevent the escape of gases from the apparatus.
- Allow the apparatus to stand in the sunlight for some time.
- Do you observe any change in the water level inside the delivery tube after forty-five minutes? Does it increase or decrease?
- Note down the final level of water in the delivery tube.
Conclusion
Germinating seeds are actively growing that require more energy. To suffice this, they perform aerobic respiration to produce energy and release carbon dioxide and water vapour as by-products. This carbon dioxide is absorbed by the KOH, thus creating a space (vacuum) in the flask for the gas molecules present in the delivery tube so these molecules move from the delivery tube into the flask releasing the pressure from the surface of water at the other end of the delivery tube. Because of this, the water molecules are able to rise in the delivery tube.
FAQs on Liberation of CO2 During Aerobic Respiration
Q.1: Why is the energy output of aerobic respiration higher than anaerobic respiration?
Answer: The energy released during aerobic respiration produces 38 ATP from one glucose molecule on its complete oxidation, whereas during anaerobic respiration, complete incomplete oxidation of glucose occurs and produces only 2 ATP as glucose is only partially broken down.
Q.2: What would happen if the rate of photosynthesis were equal to the rate of photosynthesis?
Answer: If the respiration rate is equal to the rate of photosynthesis, there will be no gross gas exchange as they will reach a compensation point.
Q.3: What is the fate of pyruvic acid during aerobic respiration?
Answer: In the first stage of respiration, called glycolysis, one molecule of glucose is broken down into two molecules of three carbon atoms containing pyruvic acid. Each pyruvic acid molecule is then oxidatively decarboxylated by the enzyme pyruvate dehydrogenase. The pyruvate dehydrogenase releases one molecule of carbon dioxide from each pyruvic acid molecule during its conversion to Acetyl CoA.
Q.4: What would happen if KOH is discarded from the experiment?
Answer: If the KOH solution is discarded from the experimental setup, the carbon dioxide produced during the respiration process shall not be consumed; therefore, there would be no change in the water level.
Q.5: When is the first carbon dioxide molecule liberated during aerobic respiration?
Answer: During aerobic respiration, the first molecule of carbon dioxide is liberated during pyruvate oxidation. Pyruvate is broken down into acetate and linked to Co A to form acetyl Co A.
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