Check sibling questions

DDT was sprayed in a lake to regulate breeding of mosquitoes. How would it affect the trophic levels in the following food chain associated with a lake? Justify your answer.

Question 7 Choice 1.jpg



Biological Magnification-01.jpg

● DDT being a non- biodegradable pesticide will enter the food chain from the first trophic level i.e. Plankton. 

● Non – biodegradable pesticides accumulate progressively at each trophic level. This phenomenon is known as biological magnification. 

● HAWK will have the highest level of pesticide.


Trophic Level means

Various steps in food chain where transfer of food or energy takes place

Each step in trophic level represents an organism


In the given question,

Plankton will be eaten by Small Fish which will be eaten by Large Fish who will be eaten by Hawk

So following are trophic levels


(Fourth trophic level)


Large fish

(Third trophic level)


Small Fish

(Second trophic level)



(First Trophic Level)


Aquatic Environment means

An ecosystem which is surrounded by water

It includes water bodies as well as aquatic plants and animals

It is not a part of trophic level


DDT is a non degradable pesticide which affects the health of plants as well as animals

Spraying of DDT in lake will be absorbed by plankton

(Plankton is a plant which is eaten by Small fish

Small fish is eaten by Large Fish who are eaten by Hawk)

These non degradable pesticides accumulate progressively at each trophic level

It is lowest at first trophic levels (plankton) and highest at last trophic level

Hence, there is Increase in concentration of harmful chemical substances at each trophic level is called biological magnification

This phenomena is called biological Magnification



Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class

Ask a doubt
Maninder Singh's photo - Co-founder, Teachoo

Made by

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo