Question

What is anaerobic respiration? How would you demonstrate it experimentally?

Answer 1

Anaerobic respiration takes place in absence of oxygen, whilst aerobic respiration occurs in presence of oxygen. Glucose is partially broken down. It is a fast process as compared to aerobic respiration.

Complete answer:
1. Anaerobic respiration is incomplete oxidation of glucose. It takes place in total absence or less amount of oxygen. Glucose is converted into pyruvate by glycolysis and further broken down to lactic acid or alcohol and carbon dioxide (i.e. decarboxylation followed by reduction).
In cells, breakdown of glucose (food we eat) occurs without use of oxygen, which gives us energy to perform various activities. This process of breakdown of glucose into carbon dioxide, alcohol, water and energy, without help of oxygen, is known as anaerobic respiration.
2. A simple example can be of muscle cells. When we do heavy exercise like running, fast walking, etc. our body needs a high amount of energy. But as there is less supply of oxygen to produce more energy, our body uses anaerobic respiration. So here, glucose is broken down into lactic acid and energy, using less amount of oxygen.
3. Anaerobic respiration can be demonstrated experimentally as follows:
Take 10% sucrose solution in a fermentation tube (Kunhe’s tube). Mix it with some amount of baker’s yeast, or take 5ml (approx.) suspension of yeast cells.
Cover the other end of the tube with a cotton ball.
You will now be able to see that fermentation taking place in the arm of the fermentation tube. Carbon dioxide gas is released and collected. This completes the demonstration of anaerobic respiration in yeast cells.

Note:
Anaerobic respiration gives out toxic end products like ethanol and ethyl alcohol.
It occurs in both eukaryotic as well as prokaryotic cells.
By keeping these key points in mind, it would be easy to understand anaerobic respiration better.