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Human Health and Disease — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYHuman Health and Disease1 Mark
MCQ
For question two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : Skin forms the first tine of defence.
Reason: It is a non$-$specific defence.
  • A
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • ✓
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • C
    Assertion is true but reason is false.
  • D
    Both assertion and reason are false.
✓

Answer

Correct option: B.
Both assertion and reason are true but reason is not the correct explanation of assertion.
Skin acts as the first line of defence because it provides a protective covering to the body against the entry of microorganisms. Its action is not specific to a particular organism. Skin forms the first$-$line of defence because $-$ It forms the hard, keratinized outer layer of the body and form effective barrier for most bacteria and viruses. The secretion of oil and sweat glands make the surface $pH$ acidic which does not let microorganisms to survive for long.The salts and fatty acids present in perspiration contain lysosomes that destroy the bacterial cell wall. It contains friendly bacteria, also release acids and other metabolic wastes which also inhibit the multiplication of organisms.

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