Question

Choose the correct option from the below about food chain:
i) The flow of energy is not unidirectional in the food chain.
ii) The size of any food chain is usually restricted to 3-5 trophic levels.
iii) For food chains to sustain, the inorganic nutrients must keep circulating.
iv) As the trophic level increases, the size of the population decreases.

Answer 1

Hint: Food chain is the sequential process of transfer of food and energy from one organism to another organism. When many food chains combine, they form a food web.

Complete answer:
The food chain usually consists of 3-4 levels. the food chain consists of following organism:
Producers: these are called primary producers. Mostly plants, phytoplankton in aquatic food chain and dead organic matter in detritus food chain. They are mostly autotrophs, that is they synthesize their own food.
Consumers: these are organisms which consume the primary producer and are known as primary consumers.
Secondary consumer consumes the primary consumer and the tertiary consumer consumes the secondary consumer.
Features of food chain:
The food chain consists of 3-5 trophic levels,
Theses food chain are straight and upright
Only $10\%$ of energy is transferred from one trophic level to another, rest is consumed in body metabolism and heat.
The population keeps on decreasing as we go up.
The energy flow is unidirectional, that is energy flow in one direction.
Hence from all the above options we can see option i) is incorrect, that is energy flows unidirectional.

Therefore, option i) is correct

Note:
The detritus food chain starts with dead organic matter. Decomposers feed on them and help in decomposition of plants and animals.