Which one among the following statements is correct? In digestive system of living organisms

In the digestive system of living organisms, proteins are broken down into their constituent amino acids. This process begins in the stomach with enzymes like pepsin and continues in the small intestine, where pancreatic juice containing trypsin and intestinal juices further hydrolyze polypeptides into amino acids for absorption [6]. While glucose is a central molecule in metabolism, it is not broken down into glycerol; rather, fats are broken down into fatty acids and glycerol [5]. The conversion of glucose into glycogen (glycogenesis) is a storage process occurring primarily in the liver and muscles, not a primary digestive breakdown [4]. Furthermore, the breakdown of glucose into carbon dioxide and water occurs during cellular respiration within cells to release energy, which is distinct from the extracellular process of digestion in the alimentary canal [5].

Sources

1. [5] https://www.ncbi.nlm.nih.gov/books/NBK482303/
2. [6] https://www.ncbi.nlm.nih.gov/books/NBK556047/
3. [4] https://www.sciencedirect.com/topics/immunology-and-microbiology/gluconeogenesis
4. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 10: Life Processes in Plants > 10.4 Do Plants Respire? > p. 149
5. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.5 > p. 87