Which of the following biomolecules is common to respiration­mediated breakdown of fats, carbohydrates and proteins?

(d) : Carbohydrates are usually first converted into glucose before they are used for respiration. Fats are broken down into glycerol and fatty acids first. If fatty acids were to be respired they would first be degraded to acetyl \(CoA\) and enter the pathway. Glycerol would enter the pathway after being converted to \(3\) ­phosphoglyceraldehyde \((PGAL)\). The proteins are degraded by proteases toindividual amino acids (after deamination) and depending on their structure enter the pathway within the Krebs’ cycle or as pyruvate or acetyl \(CoA\). Thus, acetyl \(CoA\) is the common metabolite of all the three (carbohydrates, proteins and fats).The given flowchart shows these interrelationships: