Answer: 1. Oxygen is used by cells to make energy.
2. Lungs, pharynx, larynx, trachea, bronchi, and diaphragm.
3. Blood carries oxygenated blood to the body and deoxygenated blood back to the lungs.
4. Increased amount of carbon dioxide lowers the pH of blood. Brain sends signal to the diaphragm to increase activity to get rid of carbon dioxide.
5. In the alveoli, oxygen and carbon dioxide move from high concentration to low concentration (this is also known as diffusion)
Explanation: Good luck! :D
