Both statements I and II are correct

S-I: Cellular respiration is a key metabolic process that acts as a crossroad where catabolic pathways converge and break down organic molecules (such as glucose, fatty acids, and amino acids) to extract energy stored in their chemical bonds.  Subsequently, the energy released during these catabolic reactions is used to fuel anabolic pathways, where larger molecules are synthesized from smaller ones, typically consuming ATP. 

S-II: e primary purpose of cellular respiration, which is to break down food molecules, such as glucose, and other fuel sources to produce ATP. ATP is the universal energy carrier in cells, and it is used to power various cellular processes. Cellular respiration, through the series of catabolic reactions, extracts energy from the breakdown of fuel molecules and utilizes that energy to form ATP through oxidative phosphorylation.