Question

The first trophic level in an ecosystem consists of
A. Primary producers
B. Primary consumers
C. Secondary producers
D. Secondary consumers
E. Top carnivores

Answer 1

Hint: Organisms occupy a place in a community according to their feeding relationship with other organisms. The organisms derive the nourishment either from the same source or obtaining their nourishment from the sun by the same number of steps belonging to the same trophic level.

Complete answer:
Trophic levels are the levels at which organisms obtain their food. Each trophic level has a specific mode of obtaining food. The various trophic levels are:
-First trophic level- It includes the producers which derive their nourishment from the sun.
-Second trophic level- It includes the herbivorous animals or primary consumers that derive their nourishment from the producers.
-Third trophic level- It includes all the primary carnivores or secondary consumers.
-Fourth trophic level- It includes all the secondary carnivores or tertiary consumers.
-Fifth trophic level- It includes the quaternary consumers.
-Sixth trophic level- It includes the decomposers and this is also called the detritus trophic level.
An ecosystem has few trophic levels because there is loss of food energy at each transfer which follows ten percent law. Large part of energy available is used in respiration to provide energy to maintain metabolic functions of an organism. The respiration cost increases along successive trophic levels of a food chain. So the residual energy decreases at successive trophic levels in the food chain.
So, the correct answer is “Option A”.

Note: The food is not utilized completely by an organism of a trophic level. Some part of the food material goes to waste.