Alveoli are tiny balloon shaped structures and are the smallest passageway in the respiratory system. The alveoli are only one cell thick, allowing the relatively easy passage of oxygen and carbon dioxide (CO2) between the alveoli and blood vessels called capillaries.
Three climate zones which are polar, temperate, and tropical. hope this helps
Answer:
D
Explanation:
19.6 newtons
A 2.00-kilogram object weighs 19.6 newtons on Earth.
Low levels of fecal coliform
