Where does all the energy
originally come from for living
things?

The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers, such as plants and algae, use energy from sunlight to make food energy by combining carbon dioxide and water to form organic matter.

Explanation:

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.