Explanation:
The circulatory and respiratory systems work together to circulate blood and oxygen throughout the body. Air moves in and out of the lungs through the trachea, bronchi, and bronchioles. Blood moves in and out of the lungs through the pulmonary arteries and veins that connect to the heart.
Multiple species aka animals, humans, plants and all the species interactions :)
Runoff is the stage of hydrologic cycle
Because some decompose and are gone forever.
