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Answer the following. (Class 10 Science 2023, Q29B)

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ScienceCBSE Class 10 · Board exam 2023, set 31/4/1 · 3 marks · Short answer

CBSE Class 10 Science 2023: question 29(B)

Set in the CBSE Class 10 board exam of 2023, paper 31/4/1, section C, question 29(B), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q29(B) · 3 marks · Short answerLife Processes

Answer the following.

  1. (i)

    What is double circulation ?

    1 mark
  2. (ii)

    Why is the separation of the right side and the left side of the heart useful ? How does it help birds and mammals ?

    2 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/4/1.

Hints

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

Hint 1

Count how many times blood enters the heart in one round trip of the body.

Hint 2

Which side of the heart carries oxygen-rich blood and which carries oxygen-poor blood?

Hint 3

Birds and mammals are warm-blooded. What does that demand from their oxygen supply?

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) Double circulation: blood passes through the heart twice in one complete cycle through the body. It goes once through the pulmonary circuit (heart → lungs → heart) and once through the systemic circuit (heart → body → heart).

    1 mark

  2. (ii) Separating the right and left sides keeps oxygenated blood (left side) from mixing with deoxygenated blood (right side). This allows a highly efficient supply of oxygen to the body.

    1 mark

  3. This helps birds and mammals because they have high energy needs. They constantly use energy to maintain a constant body temperature, so they need an efficient oxygen supply.

    1 mark

Answer: (i) Blood passes through the heart twice per cycle; (ii) Prevents mixing of oxygenated and deoxygenated blood, giving efficient oxygen supply needed by warm-blooded birds and mammals with high energy needs

Where the marks are

  • Definition of double circulation (1 mark)
  • Prevents mixing of oxygenated and deoxygenated blood (1 mark)
  • Meets high energy needs / body temperature maintenance in birds and mammals (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 paper2023 board paper, set 31/4/1: 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.