Assertion (A) : Accumulation of harmful chemicals is maximum in the organisms at the highest trophic level of a food chain. Reason (R) : Harmful chemicals are sprayed on the crops to protect them from diseases and pests.
Assertion (A) : Accumulation of harmful chemicals is maximum in the organisms at the highest trophic level of a food chain. Reason (R) : Harmful chemicals are sprayed on the crops to protect them from diseases and pests.
Options
Official answer
Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
Marking scheme
- 1.1 mark for selecting the correct option (b).
Hint
Does the fact that chemicals are sprayed on crops explain why they get *more concentrated* at the top of the food chain?
Quick oral answer
Biological magnification occurs because harmful chemicals are non-biodegradable; they cannot be excreted or metabolized, so they accumulate at each successive trophic level.
Common mistakes
- 1.Selecting (a) because both statements are true and related to chemicals.
- 2.Confusing the entry point of a chemical with the mechanism of its magnification.
Analysis and explanation
- Assertion (A) is true: This phenomenon is known as 'Biological Magnification'. Harmful, non-biodegradable chemicals (like pesticides) increase in concentration as we move up the food chain, reaching maximum levels in top predators (highest trophic level).
- Reason (R) is true: Chemicals are indeed sprayed on crops to protect them, and this is how they enter the food chain.
- Relationship: While (R) explains how the chemicals enter the system, it does not explain why they accumulate more at the highest level. The accumulation is due to the chemicals being non-biodegradable and the fact that organisms at higher trophic levels consume many organisms from the lower levels. Therefore, (R) is not the correct explanation for (A).
Interesting facts
Humans, being at the top of many food chains, often have the highest concentrations of these harmful chemicals in their bodies.
Question details
Q18 of 39 questions
- Board
- CBSE
- Class
- Class 10
- Subject
- Science
- Year
- 2024
- Section
- Section A
- Marks
- 1
- Type
- MCQ
- Chapter
- Chemical Reactions and Equations
- Topic
- Our Environment
- Bloom's level
- Understanding
- Syllabus topic
- Biological Magnification
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Frequently asked questions
How many marks does this question carry in CBSE Class 10 Science 2024?
This question carries 1 mark in the CBSE Class 10 Science 2024 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Chemical Reactions and Equations" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Our Environment" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2024 paper?
This is a MCQ question from Section A in the CBSE Class 10 Science 2024 paper.