It is necessary to digest the food we eat in order to give us the energy and nutrients needed for each of our cells to live.

Yes.
Most of the food we eat is not in the suitable form for our body to assimilate with the cells, therefore we need to digest the complex and insoluble food into simple, small food molecules. Examples include enzyme amylase digesting carbohydrates into Maltose then glucose.

Competition. interaction among organisms that compete for the same natural resource (food, shelter, water, space) in an ecosystem. predation. an interaction in which one organism kills another for food. predator. prey. symbiosis. mutualisum. commensalisum. parasitisum.

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