What is the primary role of the respiratory system in living organisms?
a. to make carbon dioxide
b. to obtain oxygen
c. to use up nitrogen
d. to find hydrogen

What are the characteristics of living things

What are some possible short and long term medical concerns for crew members on longer space exploration trips

When is your respiration rate likely to change? a. when your intestines are digesting b. when your cells have too much glucose c. when your cells need more oxygen d. when your liver is working after a meal