When focusing on a slide, ALWAYS start with either the 4X or 10X objective. Once you have the object in focus, then switch to the next higher power objective.
Answer:
Gas exchange between tissues and the blood is an essential function of the circulatory. The air contains oxygen that crosses the lung tissue, enters the bloodstream, and the alveoli are in direct contact with capillaries of the circulatory system. As water flows over the gills, oxygen is transferred to blood via the veins.
Explanation:
