What are the two reactants needed for respiration to occur?

Which label correctly identifies what x represents in the concept map?

What happens as electrons move along the chain of molecules known as the electron transport chain? they gain energy, which causes atp molecules to lose phosphate groups. they gain energy, which causes h *ions to join with oxygen to produce water. they lose energy, which is then used by the cell to make atp. they lose energy, which is then used to break down atp.

Which of the following explains why a tree is often used as a model to represent the principle of common descent