What is the ultimate source of energy of almost any terrestrial food chain or food web?

The ultimate source of energy (for most ecosystems) is "the sun". The ultimate fate of energy in ecosystems is for it to be lost as heat. Energy and nutrients are passed from organism to organism through the food chain as one organism eats another. Decomposers remove the last energy from the remains of organisms.

Hope this helps!

Wikipedia aswell can be used to solve the following questions