Answer:
The stomach produces hydrochloric acid.It kills many harmful microorganisms that might have been swallowed along with the food.The enzymes work best in acidic conditions-at low pH
Exchange of gases in fish is very efficient because of: the large surface area of the gills. the large surface area of the blood capillaries in each gill filament. the short distance required for diffusion – the outer layer of the gill filaments and the capillary walls are just one cell thick.
Carbon dioxide, water,<span> chlorophyll, light </span>
