Producers rely on light because that is what they use to "produce" food. Consumers, however, also rely on light, because first of all they need to see, and second of all, the light fuels growth of producers, which in turn, when consumers eat the producers, promote growth of other consumers.
Great question :)
Answer: billions of types of proteins
The eons that make up 90% of Earth's history are the Precambrian eons, which consists of Hadean, Archean, and Proterozoic eons.
