Earths atmosphere is moderately dense and is composed of 78 percent oxygen and 21 percent nitrogen true or false

If you eat to much it could kill you.

A- a reduction in biodiversity

1. protection 2. homeostasis 3. storage4.blood formation5.bone marrow 6.movement

Air enters through the nose (and sometimes the mouth), moves through the nasal cavity, the  pharynx, the  larynx, enters the  trachea, moves through the  bronchi  andbronchioles  till the alveoli.