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Biological magnification

This type of question, asked 4 times: 2023, 2024, 2025, 2026. All 11 questions below, oldest first.

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  1. Question 1

    2023

    26
    How do harmful chemicals get accumulated progressively at each trophic level in a food chain ?

  2. Question 2

    2023

    26
    Use of several pesticides which results in excessive accumulation of pesticides in rivers or ponds, is a matter of deep concern. Justify this statement.

  3. Question 3

    2023

    33
    If a harmful chemical enters in a food chain comprising peacock, plants, rats and snakes, which of these organisms is likely to have the highest concentration of the chemical in its body. Justify your answer. Name the process involved and define it.

  4. Question 4

    2024

    Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
    18
    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.

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  5. Question 5

    2025

    26
    “Excessive use of chemicals and pesticides in agriculture adversely effect the environment.” Justify this statement.

  6. Question 6

    2025

    25
    Study the food web given below : (a) Identify the food chain(s) in which the eagle receives the highest energy from the producers. (b) Identify the organism in which a non-biodegradable pesticide will be found in maximum concentration. Name the term used for this phenomenon.

  7. Question 7

    2025

    16
    Which one of the following gets biomagnified at different levels in a food chain ?

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  8. Question 8

    2026

    6
    In accumulation of toxic substances at higher trophic levels of an ecosystem through the food chain, which of the following organisms is affected the most ?

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  9. Question 9

    2026

    Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
    9
    Assertion (A) : Highest percentage of pesticides is found in tertiary consumers in a food chain. Reason (R) : Chemicals / pesticides get accumulated progressively at each trophic level.

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  10. Question 10

    2026

    6
    In the given figure, identify the trophic level having maximum concentration of harmful chemicals.

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  11. Question 11

    2026

    14
    (a) Mention any one harmful effect of using plastic bags on the environment. Suggest better alternatives to the usage of plastic bags. (b) Paddy fields require a large amount of water. The pesticides and chemical fertilizers used are washed down into the soil or waterbodies. How do these chemicals reach our bodies ? What is this phenomenon known as ?