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Humans have innate immunity… (Class 12 Biology 2025, Q20b)

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BiologyCBSE Class 12 · Board exam 2025, set 57/7/1 · 2 marks · Very short answer

CBSE Class 12 Biology 2025: question 20(b)

Set in the CBSE Class 12 board exam of 2025, paper 57/7/1, section B, question 20(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q20(b) · 2 marks · Very short answerHuman Health and Disease

Humans have innate immunity for protection against pathogens that may enter the gut along with food. What are the two barriers in our body that protect it from such pathogens ?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 57/7/1.

Hints

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

Hint 1

These are physiological and physical barriers of innate immunity.

Hint 2

Think of a secretion lining the gut and of the stomach's acidity.

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. Mucus coating of the epithelium lining the gastrointestinal tract. It traps microbes that enter with food.

    1 mark

  2. Hydrochloric acid in the stomach. Its acidity kills most pathogens swallowed with food. Saliva in the mouth is another acceptable barrier.

    1 mark

Answer: Mucus coating of the gut lining, and acid in the stomach (or saliva in the mouth).

Where the marks are

  • Mucus coating of the gastrointestinal tract (1 mark)
  • Acid in the stomach or saliva in the mouth (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Human Health and Disease, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 57/7/1: 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.