Question

Explain the process of break down of glucose in a cell

(i) in the presence of oxygen (ii) in the absence of

oxygen.​

Answer 1

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.

(Refer to the pic attached in the end )

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:

Answer 2

At first, glucose is broken down into three-carbon molecule called pyruvate.

This process happens in the cytoplasm of cells of all organisms.

On the basis of presence or absence of oxygen.

(i) Aerobic respiration takes place in the mitochondria in the presence of oxygen. Pyruvic acid is converted into carbon dioxide, and water thus releasing a lot of energy.

(ii) Anaerobic respiration takes place in the cytoplasm in the absence of oxygen.

Pyruvic acid is converted either into CO2 and ethanol

(in case of microbes, i.e., fermentation in yeast) or

into lactic acid

(in the case of muscle cells during sudden activity in humans.)