Answer:
Mitochondria convert chemical energy, in the form of a chemical called adenosine triphosphate or ATP for short. ATP is an energy currency that every cell in our body can use. ... Electrons are passed between the complexes of the electron transport chain and enable the cells to convert energy.
so it's 2nd (light to glucose)
The different blood vessels; First, Arteries that carry the blood from the heart. Then, the Capillaries which allow an exchange of water and chemicals throughout the blood and the tissues. Finally, Veins that carry blood from the capillaries to the heart.
I would say almost all types of muscles. Skeletal, cardiac, or smooth, they all need neurons. Without them, it could cause flaccid and spastic paralysis, or other types of diseases.