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Assertion (A) : Blood… (Class 10 Science 2023, Q19)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 1 mark · Assertion-reason

CBSE Class 10 Science 2023: question 19

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section A, question 19, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q19 · 1 mark · Assertion-reasonCompetency-basedLife Processes

Assertion (A) : Blood clotting prevents excessive loss of blood.
Reason (R) : Blood clotting is due to blood plasma and white blood cells present in the blood.

  1. (A)Both (A) and (R) are true and (R) is the correct explanation of (A).
  2. (B)Both (A) and (R) are true, but (R) is not the correct explanation of (A).
  3. (C)(A) is true, but (R) is false.
  4. (D)(A) is false, but (R) is true.

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

Which blood component plugs leaks at the site of a wound?

Hint 2

What is the main job of white blood cells?

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. Clotting seals a leak in a blood vessel and prevents excessive blood loss. So (A) is true.

  2. Clotting is brought about by platelets, not by plasma and white blood cells. WBCs fight infection. So (R) is false, and the answer is (C).

    1 mark

Answer: Option (C)

Where the marks are

  • A true and R false, since platelets cause clotting (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 31/1/1: 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.