Answer:
Natural cycle: a natural process which regulates Earth's systems. Solar cycle: changes in the amount of activity on the sun's surface. Carbon dioxide goes through natural cycles over hundreds of thousands of years. ... Earth goes through many natural cycles and climate is no exception.
Explanation:
It is on the organ level. The heart consists of cardiac muscle tissue and is part of the cardiovascular organ system. It is basic for the human body to work properly since it provides oxygen for the human body.
They have more than one cells
They have the ability to produce their own food
they do not have a membrane bound nuclei
electromagnetic radiation
