The endosymbiotic theory provides an explanation for the evolution of chloroplasts and mitochondria within eukaryotic cells.
This hypothesis posits that eukaryotes developed through a mechanism in which different types of free-living prokaryotes were absorbed into larger prokaryotic cells, eventually transforming into chloroplasts, mitochondria, and other organelles.
When stimulated, the stomach's environment is characterized as acidic. It secretes protease enzymes and hydrochloric acid to assist digestion. The hydrochloric acid keeps the pH low, enabling protease enzymes to effectively break down proteins. Following digestion, the stomach returns to its normal pH level. Therefore, acid secretion coincides with food presence to support proper digestion.
