Q.165 Zoology ⭐ 360° Option Elimination Active

NEET 2026 Zoology Question 165 Solution

Topic: Human Health and Disease · Official NTA Booklet Code 50

Question

Which of the following are secondary lymphoid organs? (a) Bone marrow (b) Tonsils (c) Spleen (d) Thymus Choose the correct answer from the options given below:

(1)(a) and (b) only
(2)(b) and (c) only
(3)(b) and (d) only
(4)(a) and (d) only

✓

Verified Against NTA Final Answer Key

Option (2) : (b) and (c) only

📚 Human Health and Disease Easy

📋 Given Parameters & Problem Setup

Category Secondary Lymphoid Organs in Human Body

Candidate Organs (a) Bone marrow, (b) Tonsils, (c) Spleen, (d) Thymus

⚡

The 30-Second Exam Hall Shortcut: ⚡ Primary Duo vs. Secondary Battlegrounds

⏱️ Save ~35 seconds

Primary = Bone Marrow + Thymus (Birth & School); Secondary = Spleen + Tonsils + Lymph Nodes (Warzones)!

1 Classify the 4 organs into Primary and Secondary.

2 Primary Lymphoid Organs (origin and maturation of lymphocytes): Bone marrow (a) and Thymus (d).

3 Secondary Lymphoid Organs (site of interaction with antigen): Spleen (c), Tonsils (b), Lymph nodes, Peyer’s patches, MALT.

4 Target: Secondary organs = (b) Tonsils and (c) Spleen.

5 Match Option (2): (b) and (c) only.

6 Answer locked in under 10 seconds!

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Human Health and Disease (Autoimmune Diseases: Rheumatoid arthritis damages self-joints).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Primary Lymphoid Organs

The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes.

\text{Primary Organs} = \text{Bone Marrow } (a) + \text{Thymus } (d) \implies \text{Maturation & Differentiation}

• All blood cells including B and T lymphocytes are produced in the bone marrow; T-lymphocytes mature in the thymus.

Step 2

Secondary Lymphoid Organs

After maturation, lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer’s patches of small intestine, and appendix. These organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells.

\text{Secondary Organs} = \text{Tonsils } (b) + \text{Spleen } (c) \implies \text{Antigen Interaction & Proliferation}

• The spleen is a large bean-shaped organ containing lymphocytes and phagocytes, acting as a filter for blood-borne microorganisms.

⭐

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. Bone marrow (a) is a primary lymphoid organ.

⚠️

Student Fallacy (Why candidates pick this trap): Mixing up primary bone marrow with secondary tonsils.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

100% correct. Both tonsils (b) and spleen (c) are secondary lymphoid organs.

💡

Why this is airtight: None; precise textbook classification.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Thymus (d) is a primary lymphoid organ where T-cells undergo selection.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing primary thymus with secondary spleen.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Bone marrow (a) and thymus (d) are PRIMARY lymphoid organs, not secondary.

⚠️

Student Fallacy (Why candidates pick this trap): Inverting the question prompt to pick primary organs instead of secondary.

⚠️

NTA Trap Alert: Inverting Primary vs. Secondary Prompt

Students frequently read "lymphoid organs" and instinctively select the famous pair Bone marrow + Thymus (Option 4), forgetting that those are PRIMARY, not SECONDARY.

🛡️ How to avoid the -1 mark: Circle SECONDARY: Secondary = Spleen, Tonsils, Lymph nodes (battlegrounds).

📖

Core NEET Syllabus Standard

NEET Biology Core Syllabus · Human Health and Disease Standard Benchmark

Core Scientific Principle Tested:

"Primary organs are bone marrow and thymus; secondary organs are spleen, lymph nodes, tonsils, and Peyer’s patches."

Syllabus Focus: Lymphoid Organs

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Primary = BM & T (Baby Makers); Secondary = Spleen & Tonsils (Street Fighters)!

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NEET 2026 Zoology Question 165 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Primary Duo vs. Secondary Battlegrounds

Step-by-Step Rigorous Workflow & Mathematical Proof

Primary Lymphoid Organs

Secondary Lymphoid Organs

360° Option Elimination Engine Key Feature

NTA Trap Alert: Inverting Primary vs. Secondary Prompt

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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