The gastric mucosa secretes the inactive enzyme pepsinogen and hydrochloric acid (HCl). In the presence of HCl, the active enzyme pepsin is produced. Pepsin digests proteins into shorter polypeptides. The high concentration of HCl from the parietal cells makes gastric juice very acidic, with a pH of less than 2.he gastric mucosa secretes the inactive enzyme pepsinogen and hydrochloric acid (HCl). In the presence of HCl, the active enzyme pepsin is produced. Pepsin digests proteins into shorter polypeptides. The high concentration of HCl from the parietal cells makes gastric juice very acidic, with a pH of less than 2.
Coral reef. Coral reef, ridge or hummock formed in shallow ocean areas by algae and the calcareous skeletons of certain coelenterates, of which coral polyps are the most important. A coral reef may grow into a permanent coral island.
A tsunami is a huge wave, usually caused by volcanic or earthquake activity under the ocean, which can eventually crash onto the shoreline. The effects on a community can be devastating. What causes a tsunami? When an earthquake, volcano or landslide happens on the ocean floor, water is displaced. This water forms the start of the tsunami. When the waves reach shallower water: their height can increase by several metres; the shallow water slows the wave; the waves get closer together; It is hard to see that a tsunami is approaching. The most obvious sign is the coastal water retreats just before the waves reach the shore. This is actually the trough of the wave following behind.