Q.151 Zoology ⭐ 360° Option Elimination Active

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NEET 2021 Zoology Question 151 Solution

Topic: Biomolecules · Official NTA Booklet Code M1

Question

Identify the incorrect pair.

(1)Alkaloids - Codeine
(2)Toxin - Abrin
(3)Lectins - Concanavalin A
(4)Drugs - Ricin

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Verified Against NTA Final Answer Key

Option (4) : Drugs - Ricin

📚 Biomolecules Easy

📋 Given Parameters & Problem Setup

Category-Compound Pairs (1) Alkaloids - Codeine, (2) Toxin - Abrin, (3) Lectins - Concanavalin A, (4) Drugs - Ricin

Question Objective Identify the incorrect secondary metabolite pair

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The 30-Second Exam Hall Shortcut: ⚡ "AT-LD Mnemonic: Abrin & Ricin are Toxins, Vinblastin & Curcumin are Drugs"

⏱️ Save ~25 seconds

Ricin and Abrin are deadly cellular toxins (ribosome-inactivating proteins), NOT drugs. Canonical NCERT secondary metabolite drugs are Vinblastin and Curcumin. Option (4) is immediately spotted as the incorrect pair!

1 Recall secondary metabolite categories: Alkaloids (Morphine, Codeine), Toxins (Abrin, Ricin), Lectins (Concanavalin A), Drugs (Vinblastin, Curcumin).

2 Verify Pair (4): Ricin is paired with Drugs. Ricin is a deadly plant toxin from Ricinus communis, not a drug.

3 Select Option (4).

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Why You Can 100% Trust This Shortcut: NCERT Biology · Biomolecules (Secondary metabolites classification: Abrin and Ricin are toxins; Vinblastin and Curcumin are drugs).

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Classification of Secondary Metabolites

Plants, fungi, and microbes synthesize thousands of organic compounds not directly involved in primary growth, termed secondary metabolites. NCERT organizes them into distinct functional chemical classes: - Pigments: Carotenoids, Anthocyanins - Alkaloids: Morphine, Codeine - Terpenoids: Monoterpenes, Diterpenes - Essential oils: Lemon grass oil - Toxins: Abrin, Ricin - Lectins: Concanavalin A - Drugs: Vinblastin, Curcumin - Polymeric substances: Rubber, Gums, Cellulose

\text{Secondary Metabolites} \implies \begin{cases} \textbf{Toxins:} & \text{Abrin, Ricin} \\[3pt] \textbf{Drugs:} & \text{Vinblastin, Curcumin} \\[3pt] \textbf{Lectins:} & \text{Concanavalin A} \\[3pt] \textbf{Alkaloids:} & \text{Morphine, Codeine} \end{cases}

Step 2

Critical Dissection of Pair (4)

Pair (4) lists "Drugs - Ricin". Ricin is a carbohydrate-binding protein (toxin) produced in the seeds of the castor oil plant (*Ricinus communis*). It inactivates eukaryotic 60S ribosomal subunits, causing fatal inhibition of protein synthesis. It is classified strictly as a Toxin, not a drug. The genuine medicinal drugs listed in NCERT are Vinblastin (anticancer vinca alkaloid) and Curcumin (anti-inflammatory compound from turmeric).

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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 1

✗ Incorrect

Verdict & Scientific Reason:

This pair is completely correct. Codeine and morphine are classic plant alkaloids derived from Papaver somniferum.

⚠️

Student Fallacy (Why candidates pick this trap): Students confuse alkaloids with drugs because codeine is used in cough syrups, forgetting NCERT explicitly lists Morphine and Codeine under Alkaloids.

2 2

✗ Incorrect

Verdict & Scientific Reason:

This pair is completely correct. Abrin is a ribosome-inactivating toxic protein obtained from Abrus precatorius seeds.

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Student Fallacy (Why candidates pick this trap): Candidates mistakenly think abrin is an essential oil or lectin due to unfamiliarity with Abrus precatorius.

3 3

✗ Incorrect

Verdict & Scientific Reason:

This pair is completely correct. Concanavalin A is a carbohydrate-binding plant lectin extracted from the jack bean.

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Student Fallacy (Why candidates pick this trap): Aspirants often forget the definition of lectins as carbohydrate-binding proteins and mistake Concanavalin A for a polymeric substance.

4 4

✓ 100% Correct

Verdict & Scientific Reason:

This pair is incorrect. Ricin is a toxin, not a therapeutic drug. The drugs listed in NCERT are Vinblastin and Curcumin.

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Why this is airtight: None. Ricin is a well-known chemical toxin and matches the required incorrect match.

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NTA Trap Alert: Toxin vs Drug Cross-Categorization Trap

NTA frequently swaps Abrin/Ricin (Toxins) with Vinblastin/Curcumin (Drugs) or Concanavalin A (Lectins) in match-the-column and incorrect-pair questions.

🛡️ How to avoid the -1 mark: Remember the mnemonic: "Toxic AR" (Abrin, Ricin = Toxins) and "Doctor VC" (Vinblastin, Curcumin = Drugs).

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Core NEET Syllabus Standard

NEET / NCERT Biology · Biomolecules Standard Benchmark

Core Scientific Principle Tested:

"Abrin and Ricin are classified as toxins; Vinblastin and Curcumin are classified as drugs."

Syllabus Focus: Secondary Metabolites

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2021 Zoology Question 151 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ "AT-LD Mnemonic: Abrin & Ricin are Toxins, Vinblastin & Curcumin are Drugs"

Step-by-Step Rigorous Workflow & Mathematical Proof

Classification of Secondary Metabolites

Critical Dissection of Pair (4)

360° Option Elimination Engine Key Feature

NTA Trap Alert: Toxin vs Drug Cross-Categorization Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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