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Study the food chain… (Class 10 Science SQP 2023-24, Q26)

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ScienceCBSE Class 10 · Sample paper, session 2023-24 · 2 marks · Very short answer

CBSE Class 10 Science sample paper 2023-24: question 26

From the official CBSE sample question paper for 2023-24, section B, question 26, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q26 · 2 marks · Very short answerCompetency-basedOur Environment

Study the food chain given below and answer the questions that follow:

  1. (a)

    If the amount of energy available at the third trophic level is 100 joules, then how much energy will be available at the producer level? Justify your answer.

    1 mark
  2. (b)

    Is it possible to have 2 more trophic levels in this food chain just before the fourth trophic level? Justify your answer.

    1 mark

Figure in the paper: A food chain shown with pictures in order: Leaf → Caterpillar → Chameleon → Snake → Mongoose (the arrow from Snake points to Mongoose, and the arrow from Mongoose points back toward Snake as printed, drawn as a cycle-like layout with Mongoose on the left side of the lower row). See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

Recall the 10 percent law of energy transfer.

Hint 2

Work backwards: each lower level has 10 times the energy of the level above it.

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. (a) The trophic levels are: Leaf (producer, 1st), Caterpillar (2nd), Chameleon (3rd), Snake (4th), Mongoose (5th). By the 10% law, only about 10% of the energy at one level passes to the next level.

  2. So the energy at the 2nd level is J, and at the producer level it is J. Energy at producer level = 10000 J, because only 10% of the energy is transferred to each next trophic level.

    1 mark

  3. (b) No. At each step about 90% of the energy is lost, mostly as heat. If two more levels were added before the fourth level, so little usable energy would remain that the higher levels could not be supported. That is why food chains usually have only 3–4 (rarely 5) trophic levels.

    1 mark

Answer: (a) 10000 J (10% law); (b) No, so much energy is lost at each step that too little usable energy would remain for the extra levels.

Where the marks are

  • Gives 10000 J at the producer level with the 10% law as the reason (1 mark)
  • Says 'No' and explains that energy loss at each step leaves too little usable energy (1 mark)

Revise the chapter

  • Chapter: Our Environment (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Our Environment, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2023-24: 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.