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Attempt either option… (Class 10 Science SQP 2026-27, Q16A)

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ScienceCBSE Class 10 · Sample paper, session 2026-27 · 5 marks · Long answer

CBSE Class 10 Science sample paper 2026-27: question 16(A)

From the official CBSE sample question paper for 2026-27, section A, question 16(A), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q16(A) · 5 marks · Long answerCompetency-basedLife Processes

Attempt either option A or B. A. Observe the structure of hearts A, B and C shown above and answer the following questions.

  1. I

    Which of the hearts depicted above is present in both birds and Mammals and how are they able to maintain their body temperature? Give reason for your answer.

    0 marks
  2. II

    Which of the hearts depicted above is present in fishes, how does circulation of blood take place in them?

    0 marks

Figure in the paper: Three heart diagrams labelled A, B and C. A is a single-chambered-looking structure with blue (deoxygenated) pathway only. B is a four-chambered heart with blue (deoxygenated) and red (oxygenated) sides fully separated. C is a heart with blue and red sides, with the red side partially separated. See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Look at which heart shows blue and red blood kept completely apart, and which shows them blending.

Hint 2

Warm-blooded animals need a lot of energy, so their oxygen supply must be very efficient.

Hint 3

C is the fully separated four-chambered heart; A (all blue) is the fish heart, which sends blood to the gills and then straight to the body.

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. Birds and mammals have heart C, the four-chambered heart. Its right and left sides are completely separated. (In heart B the ventricle shows mixed blue-red blood, so B is not fully separated.)

    1 mark

  2. The separation of the right and left sides keeps oxygenated and deoxygenated blood from mixing. This allows a highly efficient supply of oxygen to the body.

    1 mark

  3. Birds and mammals have high energy needs, as they constantly use energy to maintain their body temperature. The efficient oxygen supply supports the high rate of respiration that releases this energy.

    1 mark

  4. II. Fishes have heart A, the two-chambered heart.

    1 mark

  5. The heart pumps blood to the gills, where it is oxygenated. It then passes directly to the rest of the body and returns to the heart. Thus blood goes only once through the heart in one cycle (single circulation).

    1 mark

Answer: I. Heart C (four-chambered): separation of oxygenated and deoxygenated blood gives an efficient O₂ supply for the high energy used to maintain body temperature. II. Heart A (two-chambered): heart → gills → body → heart; blood passes through the heart once per cycle.

Where the marks are

  • Identifies heart C as the four-chambered heart of birds and mammals (1 mark)
  • Separation prevents mixing of oxygenated and deoxygenated blood, giving an efficient O₂ supply (1 mark)
  • Links the high energy need to maintaining body temperature (1 mark)
  • Identifies heart A (two-chambered) for fishes (1 mark)
  • Describes single circulation via the gills (1 mark)

Revise the chapter

  • Chapter: Life Processes (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Life Processes, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2026-27: 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.