Q.167 Zoology ⭐ 360° Option Elimination Active

NEET 2025 Zoology Question 167 Solution

Topic: Human Health and Disease · Official NTA Booklet Code 45

Question

Which of the following type of immunity is present at the time of birth and is a non-specific type of defence in the human body?

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Verified Against NTA Final Answer Key

Option (2) : Innate Immunity

📚 Human Health and Disease Easy

📋 Given Parameters & Problem Setup

Timing Present at the time of birth (inborn / congenital)

Specificity Non-specific type of defence mechanism

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The 30-Second Exam Hall Shortcut: ⚡ Innate vs Acquired Immunity Fingerprint

⏱️ Save ~10 seconds

Present from birth (inborn) + Non-specific defence = INNATE IMMUNITY! Acquired (adaptive) immunity develops after birth, is pathogen-specific, and has memory!

1 Recall NCERT Section 8.2.1 (Innate Immunity) opening line:

2 - "Innate immunity is non-specific type of defence, that is present at the time of birth."

3 - It provides four types of barriers: Physical (skin, mucus), Physiological (HCl, tears, saliva), Cellular (WBCs, PMNL-neutrophils, macrophages), and Cytokine (interferons).

4 - Acquired immunity is pathogen-specific, characterized by immunological memory, and acquired during lifetime.

5 Direct answer: Innate Immunity!

6 Select Option (2) Innate Immunity!

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Why You Can 100% Trust This Shortcut: Bacterial & Viral Human Pathogens (NCERT Biology · Human Health and Disease: Typhoid Salmonella typhi & Widal test).

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Definition and Attributes of Innate Immunity

Innate immunity represents the body's first line of natural immunological defence:

• It is congenital, meaning it is genetically predetermined and fully operational at the time of birth.
• It is non-specific, meaning it does not discriminate between distinct antigenic molecular determinants; it provides broad-spectrum resistance against invasion by foreign infectious agents.

Step 2

Four Barrier Categories of Innate Immunity

How non-specific protection is maintained:

• Physical barriers: Skin acts as the principal barrier preventing entry; mucus coatings of respiratory, GI, and urogenital tracts trap microbes.
• Physiological barriers: Gastric acid (HCl) in stomach, saliva in the mouth, and lysozyme in tears prevent microbial growth.
• Cellular barriers: Phagocytes like polymorphonuclear leukocytes (PMNL-neutrophils), monocytes, and tissue macrophages, plus Natural Killer (NK) cells.
• Cytokine barriers: Virus-infected cells secrete interferons which protect non-infected cells from further viral infection.

Step 3

Contrast with Acquired Immunity

Distinguishing features of adaptive defence:

• Acquired (adaptive) immunity (including humoral and cell-mediated branches) is NOT present at birth; it is acquired post-natally upon exposure to specific pathogens and is characterized by exquisite antigenic specificity and long-lasting memory.

Step 4

Conclusion

The immunity present at birth providing non-specific defence is Innate Immunity, corresponding to Option (2).

\text{Present at Birth} + \text{Non-Specific} \implies \text{Innate Immunity (Option 2)}

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360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 A

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Acquired immunity is developed after birth upon pathogen encounter and is pathogen-specific.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing adaptive immunity with congenital immunity.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

100% correct. Direct verbatim NCERT definition: non-specific defence present at the time of birth.

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Why this is airtight: None; fundamental immunology recall.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Cell-mediated immunity is mediated by T-lymphocytes and is an antigen-specific component of acquired immunity.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing cellular innate barriers with T-cell mediated acquired immunity.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Humoral immunity is antibody-mediated acquired immunity produced by B-lymphocytes post-exposure.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing antibody responses with inborn non-specific immunity.

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NTA Trap Alert: Innate vs Inborn Terminology

Innate literally means "inborn". It provides general non-specific protection from the first second of life. Acquired immunity takes days to weeks to build and requires prior antigen exposure.

🛡️ How to avoid the -1 mark: Birth + Non-specific = Innate.

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Core NEET Syllabus Standard

NEET Biology Core Syllabus · Human Health and Disease Standard Benchmark

Core Scientific Principle Tested:

"Innate immunity is a non-specific type of defence present at the time of birth."

Syllabus Focus: Immunity · Innate Immunity

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

IN-NATE = IN-BORN: Natural, Non-specific, from day 0!

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NEET 2025 Zoology Question 167 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Innate vs Acquired Immunity Fingerprint

Step-by-Step Rigorous Workflow & Mathematical Proof

Definition and Attributes of Innate Immunity

Four Barrier Categories of Innate Immunity

Contrast with Acquired Immunity

Conclusion

360° Option Elimination Engine Key Feature

NTA Trap Alert: Innate vs Inborn Terminology

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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