Answer:
what's the complete question?
Answer: The sun
Explanation:
Plants use the sun to create their food through the process of photosynthesis
Answer:
The respiratory centers that control your rate of breathing are in the brainstem or medulla. The nerve cells that live within these centers automatically send signals to the diaphragm and intercostal muscles to contract and relax at regular intervals.
Answer:
False
Explanation:
Scientist believe that the primitive atmosphere lacked free oxygen. Oxygen is a highly reactive molecule that would have made difficult for complex macromolecules to appear and then create life. Rocks from the precambrian period support this theory.
Anaerobic cells appeared first, then photosynthesis appeared filling the atmosphere with oxygen and the aerobic organism develop cellular respiration to obtain energy, a process more efficient than anaerobic respiration.
