What is the ultimate source of energy for all ecosystems?

Answer 1

The ultimate source of all energy on earth is light from the sun. Plants use that energy, along with carbon dioxide from the air and nitrates from the soil, to create sugars and lipids (fats) as well as amino acids (ingredients for DNA) through the process of photosynthesis.

Without photosynthesis, there would be nothing of nutritional value (energy) in plants for animals to digest and turn into protein (muscle tissue). Even carnivores who eat only meat depend on plants as their prey would not be alive without energy they get from eating plants, which in turn comes from light from the sun.

Answer 2

The sun.

Or the big bang.

Answer 3

oxygen