Question

Most of organisms depend directly or indirectly upon _________for food

Answer 1

Plant.

In this ecosystem, our food chain is such that every other organism depends on some other organism for food.

Plants are the basis of this food chain and are at the bottom.

They manufacture their food on their own by taking energy from the sun, in a way called photosynthesis.

Most of the animals directly or indirectly dependent on them.

Answer 2

Most of the organisms depend directly or indirectly upon plants for food.
.. So answer is : plants..