Question

The energy flow in an ecosystem is
a. Multidirectional
b. Unidirectional
c. Bidirectional
d. Circular

Answer 1

Hint: The primary source of energy in the ecosystem is the sun, where plants undergo photosynthesis by using that solar energy and produce food or energy, which will transfer to other trophic levels of the food chain.

Complete answer:
In this ecosystem energy usually enters through the sun, by using this energy plants will go through photosynthesis and produce food, the plants which produce food or energy come under the first trophic level, where this energy will be transferred to other trophic levels in the food chain.

The energy which is transferring from one organism to another is not total energy as in every trophic level the animals lost some power to the environment in the form of heat.
The energy which was lost in the form of heat will not come back again, and it can’t be used by plants for photosynthesis, so one can say that energy flow in the food chain is always unidirectional.

The energy in the food chain is always produced by plants, if we consider this energy is 100 percent in first trophic level, now in the second trophic level there are herbivores which consume plants as food, here not 100 of power will be transferred where some energy is lost to environment (10% percent of energy is usually lost at each trophic level in the food chain )
The energy which is lost cannot be reused by the plants again; this is why energy flow is always said to be unidirectional.

So the correct option is unidirectional.

Note: The critical point that should be remembered is, once plants produce energy, it will be transferred to consumers, whereas consumers lost some power during respiration, excretion, digestion etc. So whatever energy consumers lose will not return to plants, this simple basic idea will always help to remember the direction of energy in the food chain.