The human respiratory system intakes oxygen which is transported to all parts of the body by the circulatory system. then, the circulatory
system returns deoxygenated blood to the respiratory system.
at what level of organization does this interaction occur?

sunlight and water

explanation:

the "dirty dozen" chemicals banned in an international treaty are formally known as persistent organic pollutants, or pops. the united nations environment program provided this background on what they are and what they can do to humans and wildlife.

i hope this