Anaerobic respiration is a process where seeds produce energy without using oxygen. During this process, the stored food in the seed, primarily glucose, is broken down into ethanol and carbon dioxide.

The Chemistry of Anaerobic Respiration

When seeds are submerged in water, they cannot access oxygen from the air. To survive, they switch to anaerobic respiration. The chemical reaction follows this formula: C6H12O6 → 2C2H5OH + 2CO2 + 2ATP. In this equation, glucose turns into two molecules of ethanol (alcohol), two molecules of carbon dioxide gas, and two molecules of energy-rich ATP.

How Seeds Survive Without Air

Germinating seeds usually need oxygen to grow. If they are placed in a vacuum or under water, they face an oxygen shortage. Because seeds have a tough outer coat, they can withstand short periods of oxygen deprivation. However, if this continues for too long, the toxic ethanol produced will eventually kill the embryo inside the seed.

Laboratory Experiment Steps

• Fill a test tube completely with soaked gram or pea seeds.
• Invert the test tube into a beaker filled with a solution of potassium hydroxide (KOH).
• Seal the setup so no outside air can enter the tube.
• Wait for 24 to 48 hours to observe the results.

As the seeds respire, they release carbon dioxide. The potassium hydroxide in the beaker absorbs this carbon dioxide, creating a vacuum. You will notice the level of the liquid rising inside the test tube, which proves that gas was released and then absorbed.

Key Observations

If you smell the seeds after the experiment, they will have a sharp, fermented odor. This smell is caused by the ethanol produced during the anaerobic breakdown. Unlike aerobic respiration, which produces 36 units of ATP, anaerobic respiration is inefficient and only provides 2 units of ATP, making it a temporary survival strategy for the seed.