What created oxygen in the early atmosphere
photosynthetic bacteria
asteroids hitting the earth
plankton
volcanic eruptions
forests

The finches on the galapagos island were similar in form except for variations of their beaks. darwin observed that these variations were useful for: attracting a mate defending territory building nests gathering food

The picture represents a structure of the respiratory system. which is the function of this structure? to bring air into the body to exchange oxygen with carbon dioxide to carry air to the lungs to release oxygen from the body

What happens during the experiment stage of the scientific method