a scientist makes the following statement it's Earth's early atmosphere had been rich in oxygen photosynthetic organisms would have not been able to evolve which of the following statements can be used to argue against this hypothesis

Abird flies by moving its wings up and down. which two systems are most directly responsible for the movement of a bird's wings? a. skeletal and muscular systems b. respiratory and muscular systems c. skeletal and digestive systems d. respiratory and digestive systems