Explain the universal significance of producers (autotrophs) in ecosystems?

Producers are called producers because when they take in carbon dioxide and water, and they produce glucose and oxygen. Animals need oxygen to survive and producers are the reason that all of the animals on earth haven't used up all the oxygen in the atmosphere. We need producers to survive, otherwise the Earth would be carbon dioxide rich and we humans couldn't breath it.

A. because they both benefit off each other