Question

In which direction will the energy flow between sun, autotrophs, primary consumers and tertiary consumers? Where does this energy transfer stop?

Answer 1

Unidirectional flow from sun to autotrops to primary consumers then to tertiary consumers.

Energy never stops it is just transfered from one form to another.
But transfer of energy in a food chain stops temporarily at the highest trophic level. ie. tertialry consumers

Answer 2

The Sun , autotrophs, primary consumers and secondary consumers form a food chain.

The flow of energy in a food chain is always unidirectional.
The Sun provides energy to autotrophs to prepare food. This food is consumed by the primary consumer, so there is a flow of energy here.Then, the tertiary consumer consume the primary consumer and gain this energy.

The flow of energy always stop at the top occupier of food chain.In this case, the energy transfer stops at tertiary consumer.

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