What are two by products of cellular respiration

Describe some of the common health conditions associated with air pollution.

How does the endocrine system affect the body's functions? o o o o it secretes enzymes directly into the bloodstream. it secretes hormones directly into the bloodstream. it secretes enzymes through ducts to the surface of organs. it secretes hormones through ducts to the surface of organs.

The first step in treating water from a river or lake is usually