According to the law of conservation, both energy and matter are in natural systems. Earth as a whole is a
system, in which energy and matter can move from one subsystem to another.

As energy and matter are transferred between subsystems, different forms of matter and energy interact. For example, during photosynthesis, carbon is transferred from the
into the biosphere, while radiant energy from
is being converted into chemical energy. During this process, the amount of carbon remains constant, but some of the radiant energy is transformed into
energy.