The ozone layer, it keeps the UV rays out but because of us humans and the chemicals we release it is breaking down the molecules and now some harmful UV rays can come onto the earth surface
Answer:
pulmonary ventilation and external respiration
Explanation:
Respiration includes pulmonary ventilation, external respiration, and internal respiration. Pulmonary ventilation is also called breathing and is the process of flow of air into and out of the lungs. It includes the flow of air between the atmosphere and the alveoli of the lungs and is driven by alternating pressure differences created by contraction and relaxation of respiratory muscles.
External respiration is also called pulmonary respiration. It refers to the exchange of gases between the alveoli of the lungs and the blood in pulmonary capillaries. The exchange occurs through the respiratory membrane. External respiration males the capillary blood rich in O2. The capillary blood loses CO2 during the process.
Answer:
4.543 billion years
Explanation:
I looked it up on a wonderful search engine called g00gle
Answer:
No cell wall only plasma membrane.
Explanation:
The cells of animals lack wall and chlorophyll
Answer:More soldier who had lost a limb returned home.
