Explain the process of breakdown of …

The process of breakdown of glucose in a cell are as follows:

The first step in the breakdown of glucose both in presence of O₂ and in absence of O₂ is same. In this step, glucose is broken down into pyruvate. Second step which involves further breakdown of private into simple compounds can take place in two different ways:

(a) In presence of O₂: In the presence of O₂, private is converted into CO₂ and water. Energy released during aerobic respiration is much greater than that released during an anaerobic respiration. 

(b)In absence of O₂: In the absence of O₂ in yeast, pyruvate is converted into ethanol and CO₂ and the process is called fermentation. In absence of O₂, in our muscle cells, pyruvate is converted into lactic acid. The build up of lactic acid in muscle cells causes cramps.

(i) In the presence of oxygen- When breakdown of glucose is carried out in the presence of oxygen in a cell, it is called as aerobic respiration. Glucose is converted into a 3 carbon molecule called pyruvate which further breaks down in the presence of oxygen to form carbon dioxide and water. Energy is released in this process.

(ii)In the presence of oxygen- When breakdown of glucose is carried out in the Absence of oxygen in a cell, it is called as anaerobic respiration.Glucose is converted into a 3 carbon molecule called pyruvate which further breaks down in the absence of oxygen to give lactic acid and ethyl alcohol. This process is called fermentation.