Use of several pesticides which results in excessive accumulation of pesticides in rivers or ponds, is a matter of deep concern. Justify this statement.
Use of several pesticides which results in excessive accumulation of pesticides in rivers or ponds, is a matter of deep concern. Justify this statement.
Official answer
The excessive accumulation of pesticides in rivers or ponds is a matter of deep concern due to the following reasons:
- Entry into the Food Chain: Pesticides sprayed on crops are washed down into the soil or water bodies. From water bodies, they are absorbed by aquatic plants and animals, thereby entering the aquatic food chain.
- Biological Magnification: Since these synthetic chemicals are non-biodegradable, they cannot be broken down or metabolized by living organisms. Consequently, they get accumulated progressively at each successive trophic level. As human beings occupy the top level in any food chain, the maximum concentration of these harmful chemicals gets accumulated in our bodies, leading to severe health hazards. This phenomenon is known as biological magnification.
Marking scheme
- 1.1 mark
- 2.1 mark
Hint
Think about how non-biodegradable chemicals move up a food chain and where their concentration is highest.
Quick oral answer
Pesticides accumulate in water bodies and enter the food chain. Since they are non-biodegradable, their concentration increases at each trophic level, reaching the maximum in top consumers like humans. This is called biological magnification.
Common mistakes
- 1.Confusing biological magnification with eutrophication (algal bloom).
- 2.Stating that pesticides degrade or get diluted as they move up the food chain.
Analysis and explanation
Pesticides are synthetic chemicals used to protect crops from pests and diseases. When these chemicals are washed into water bodies like rivers or ponds, they are absorbed by aquatic producers (such as algae and aquatic plants). When primary consumers (like small fish) feed on these producers, the chemicals enter their bodies. Because these substances are non-biodegradable, they cannot be excreted or broken down, so their concentration increases at each higher trophic level. Since humans are at the apex of many food chains, we end up with the highest concentration of these toxic residues in our bodies, which can cause chronic illnesses and organ damage.
Interesting facts
Even if we wash our fruits and vegetables thoroughly, pesticide residues that have been absorbed internally through the roots during growth cannot be completely removed.
Question details
Q26 of 39 questions
- Board
- CBSE
- Class
- Class 10
- Subject
- Science
- Year
- 2023
- Section
- Section B
- Marks
- 2
- Type
- Very Short Answer
- Chapter
- Our Environment
- Topic
- Food Chains and Webs
- Bloom's level
- Evaluate
- Syllabus topic
- Biological magnification
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Frequently asked questions
How many marks does this question carry in CBSE Class 10 Science 2023?
This question carries 2 marks in the CBSE Class 10 Science 2023 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Our Environment" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Food Chains and Webs" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2023 paper?
This is a Very Short Answer question from Section B in the CBSE Class 10 Science 2023 paper.