(a) Define trophic level. Draw the food chain with four trophic levels.(b) What will happen if we kill all the organisms in one trophic level?

(a) Trophic Levels – The various steps in a food chain at which the transfer of food takes place are called trophic levels.

In a food chain, each step representing an organism forms a trophic level.

A food chain with four trophic levels can be shown as follows:

$Grass (Producer) \rightarrow Insect  (Herbivore) \rightarrow Frog (Carnivore) \rightarrow Bird (Large Carnivore)$

(b) If we kill all the organisms at one trophic level, then the transfer of food (and energy) to the next trophic level will stop due to which the organisms of the next trophic level will starve and die or migrate to other areas.

The killing of all the organisms in one trophic level will also lead to the overpopulation of organisms in the previous trophic level. These effects will cause an imbalance in the ecosystem.

Example: If we kill all the herbivorous animals like deer, rabbits, etc., in a forest, then the carnivorous animals like lions, tigers, etc., will not get food. Due to this, the lions and tigers, etc., will starve and die or migrate from the forest and go towards human settlements and attack people. Moreover, in the absence of herbivores like deer, rabbits, etc., the population of the previous trophic level ‘plants’ (or vegetation) will increase too much (because there are no deer or rabbits to eat them). All these effects will create an imbalance in the ecosystem.