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Answer the following. (Class 10 Science 2023, Q33b)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 3 marks · Short answer

CBSE Class 10 Science 2023: question 33(b)

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section C, question 33(b), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q33(b) · 3 marks · Short answerOur Environment

Answer the following.

  1. (i)

    Construct a food chain of four trophic levels comprising the following :
    Hawk, snake, plants, rat.

    0 marks
  2. (ii)

    20,000 J of energy was transferred by the producers to the organism of second trophic level. Calculate the amount of energy that will be transferred by organisms of the third trophic level to the organisms of the fourth trophic level.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Start the chain with the producer and end with the top predator.

Hint 2

Use the 10% law: only one-tenth of the energy passes on at each step. Apply it twice, starting from 20,000 J.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (i) Food chain: Plants → Rat → Snake → Hawk. Here plants are the producers, the rat is the primary consumer, the snake is the secondary consumer and the hawk is the tertiary consumer.

    1 mark

  2. (ii) By the 10% law, only about 10% of the energy at one trophic level is passed on to the next level.

    Energy available at the second trophic level (rat) = 20,000 J.

    Energy transferred from the second to the third trophic level (snake) of J.

    1 mark

  3. Energy transferred from the third to the fourth trophic level (hawk) of J.

    So 200 J is transferred by the third trophic level to the fourth.

    1 mark

Answer: (i) Plants → Rat → Snake → Hawk; (ii) 200 J

Where the marks are

  • Correct food chain Plants → Rats → Snakes → Hawks (1 mark)
  • Energy reaching the third level = 2000 J using the 10% law (1 mark)
  • Energy transferred to the fourth level = 200 J (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Our Environment, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.