What are the different ways in which glucose is oxidised to provide energy in various organisms?

First step takes place is breakdown of glucose in the cytoplasm giving rise to pyruvate which is a three carbon molecule.This pyruvate is further broken down in three different ways:
(a) Aerobic respiration: This involves breakdown of pyruvate in the presence of oxygen and Pyruvate gets converted into carbon dioxide and water.Release of energy in this is much more than in anaerobic respiration..Example: In mitochondria.

(b) Anaerobic respiration: This involves breakdown of pyruvate taking place in the absence of oxygen hence Pyruvate is broken down into ethanol and carbon dioxide.Example: Yeast during fermentation.

(c)Lack of oxygen:This state may be reached due to vigorous activities and leads to lack of oxygen which results in conversion of pyruvate into lactic acid(3 carbon molecule compound).Accumulation of lactic acid leads to muscle cramps.Example: In human muscle cells.