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NEET 2026 Botany Question 101 Solution

Topic: Biological Classification · Official NTA Booklet Code 50

Question

Mad cow disease is caused by.

(1)prions
(2)viroids
(3)Aspergillus sp.
(4)Mycoplasma sp.

✓

Verified Against NTA Final Answer Key

Option (1) : prions

📚 Biological Classification Easy

📋 Given Parameters & Problem Setup

Disease Mad cow disease (Bovine Spongiform Encephalopathy, BSE)

Target Causative infectious agent

⚡

The 30-Second Exam Hall Shortcut: ⚡ Proteinaceous Prion Pathology

⏱️ Save ~40 seconds

Mad cow disease = BSE = PRIONS (abnormally folded infectious proteins)!

1 Recall definition of acellular infectious agents:

2 Viruses = Genetic material (DNA/RNA) + protein coat.

3 Viroids = Free infectious low-molecular-weight RNA without protein coat (e.g. Potato spindle tuber disease).

4 Prions = Abnormally folded infectious proteins without nucleic acid (e.g. Mad cow disease / BSE in cattle, CJD in humans).

5 Option (1) is Prions! Done in 5 seconds!

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biological Classification verbatim: The most notable diseases caused by prions are bovine spongiform encephalopathy (BSE) commonly called mad cow disease in cattle and its analogous variant Cr-Jacob disease (CJD) in humans.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Define Prions and Their Pathological Nature

Prions are proteinaceous infectious agents consisting entirely of an abnormally folded version of a normal cellular prion protein (PrP^Sc). Unlike viruses and viroids, prions contain no nucleic acids (neither DNA nor RNA). When an abnormal prion enters a host, it induces normal helical proteins to misfold into beta-sheet-rich aggregates, destroying brain tissue and giving it a spongy appearance (spongiform encephalopathy).

\text{Prion} \equiv \text{Abnormally folded infectious protein (No Nucleic Acid)}

• Size: Similar in size to small viruses.

Step 2

Match Disease to Agent

1. Bovine Spongiform Encephalopathy (BSE / Mad Cow Disease): Chronic neurodegenerative disorder in cattle caused by prions. 2. Creutzfeldt-Jakob Disease (CJD): Human analog of mad cow disease, also caused by prions. 3. Potato Spindle Tuber Disease: Caused by viroids (T.O. Diener, 1971). 4. Aspergillosis: Fungal infection caused by Aspergillus. 5. Pleuropneumonia / Atypical pneumonia: Caused by Mycoplasma.

\text{Mad Cow Disease (BSE)} \longrightarrow \text{Prions}

• Prions are the definitive causative agents.

Step 3

Conclusion

Mad cow disease is caused by prions.

\text{Matches Option (1)}

• Matches Option (1).

⭐

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

✓ 100% Correct

Verdict & Scientific Reason:

Exact match with NCERT text: Bovine Spongiform Encephalopathy is caused by prions.

💡

Why this is airtight: None; standard microbiological fact.

2 B

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Viroids are naked infectious RNA molecules that cause plant diseases (e.g. Potato spindle tuber disease).

⚠️

Student Fallacy (Why candidates pick this trap): Confusing prions (infectious proteins) with viroids (infectious RNA).

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Aspergillus is a filamentous ascomycete fungus.

⚠️

Student Fallacy (Why candidates pick this trap): Thinking mad cow disease is a fungal mycosis.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Mycoplasma are cell-wall-less bacteria.

⚠️

Student Fallacy (Why candidates pick this trap): Assuming a bacterial origin for mad cow disease.

⚠️

NTA Trap Alert: Confusing Prions with Viroids

Students frequently mix up Viroids and Prions: Viroids are RNA only (discovered by Diener for potato disease); Prions are PROTEINS only (cause Mad Cow Disease and CJD).

🛡️ How to avoid the -1 mark: Remember: P for Prion = Protein (Mad Cow); V for Viroid = Virus-like RNA (Potato).

📖

Core NEET Syllabus Standard

NEET Biology Core Syllabus · Biological Classification Standard Benchmark

Core Scientific Principle Tested:

"Prions are abnormally folded proteins causing transmissible spongiform encephalopathies like mad cow disease and CJD."

Syllabus Focus: Acellular agents - Viruses, Viroids, and Prions

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

P for Prion, P for Protein, Mad Cow disease in the bovine scene!

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NEET 2026 Botany Question 101 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Proteinaceous Prion Pathology

Step-by-Step Rigorous Workflow & Mathematical Proof

Define Prions and Their Pathological Nature

Match Disease to Agent

Conclusion

360° Option Elimination Engine Key Feature

NTA Trap Alert: Confusing Prions with Viroids

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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