Q.9 Botany ⭐ 360° Option Elimination Active

NEET 2020 Botany Question 9 Solution

Topic: Animal Kingdom · Official NTA Booklet Code E1

Question

Match the following columns and select the correct option. Column - I Column - II (a) Gregarious, polyphagous (i) Asterias pest (b) Adult with radial (ii) Scorpion symmetry and larva with bilateral symmetry (c) Book lungs (iii) Ctenoplana (d) Bioluminescence (iv) Locusta (a) (b) (c) (d)

(1)(i) (iii) (ii) (iv)
(2)(iv) (i) (ii) (iii)
(3)(iii) (ii) (i) (iv)
(4)(ii) (i) (iii) (iv)

✓

Verified Against NTA Final Answer Key

Option (2) : (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)

📚 Animal Kingdom Easy

📋 Given Parameters & Problem Setup

Column I (Features) (a) Gregarious polyphagous pest, (b) Adult radial symmetry / larva bilateral, (c) Book lungs, (d) Bioluminescence

Column II (Genera) (i) Asterias, (ii) Scorpion, (iii) Ctenoplana, (iv) Locusta

⚡

The 30-Second Exam Hall Shortcut: ⚡ "Locusta = Pest, Asterias = Larva Bilateral / Adult Radial, Ctenoplana = Glows!"

⏱️ Save ~25 seconds

Locusta (locust) is a gregarious polyphagous pest ((a)-(iv)). Asterias (echinoderm starfish) has bilateral larvae and pentamerous radial adults ((b)-(i)). Scorpion breathes via book lungs ((c)-(ii)). Ctenoplana (ctenophore) emits bioluminescence ((d)-(iii)). Pattern (iv), (i), (ii), (iii) gives Option (2) instantly!

1 Match (a) Gregarious pest -> (iv) Locusta (migratory locust).

2 Match (b) Larva bilateral, adult radial symmetry -> (i) Asterias (Phylum Echinodermata hallmark).

3 Match (c) Book lungs -> (ii) Scorpion (Arachnida respiratory organ).

4 Match (d) Bioluminescence -> (iii) Ctenoplana (Phylum Ctenophora hallmark).

5 Match pattern (iv), (i), (ii), (iii) -> Option (2).

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Animal Kingdom (Phylum Arthropoda: Locusta is a gregarious pest, Scorpion respire by book lungs; Phylum Echinodermata: Adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical, e.g. Asterias; Phylum Ctenophora: Bioluminescence is well marked in ctenophores, e.g. Ctenoplana).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Diagnostic Features and Taxonomic Alignment

- (a) Gregarious, polyphagous pest: _Locusta_ (Locust, Phylum Arthropoda, Class Insecta) is an economically devastating swarming insect pest that destroys agricultural crops en masse. - (b) Larva bilateral and adult radial symmetry: Characteristic developmental hallmark of Phylum Echinodermata (_Asterias_, starfish). Free-swimming bipinnaria/dipleurula larvae exhibit primary bilateral symmetry, while adults metamorphose into pentamerous radial symmetry. - (c) Book lungs: Respiratory organs found in terrestrial arachnids such as _Scorpion_ and spiders (Phylum Arthropoda). - (d) Bioluminescence: The emission of light by a living organism, exquisitely manifested in Phylum Ctenophora (_Ctenoplana_ and _Pleurobrachia_).

\begin{aligned} \text{Gregarious pest} &\iff \textit{Locusta} \quad [\text{(a)} \to \text{(iv)}] \\ \text{Larva bilateral, adult radial} &\iff \textit{Asterias} \quad [\text{(b)} \to \text{(i)}] \\ \text{Book lungs} &\iff \textit{Scorpion} \quad [\text{(c)} \to \text{(ii)}] \\ \text{Bioluminescence} &\iff \textit{Ctenoplana} \quad [\text{(d)} \to \text{(iii)}] \end{aligned}

Step 2

Option Alignment

Matching sequence is: (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii). This corresponds uniquely to Option (2).

⭐

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. Assigns Asterias to pest and Locusta to bioluminescence.

⚠️

Student Fallacy (Why candidates pick this trap): Gross misalignment of phyla.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

Correct. Perfectly matches all 4 morphological traits with their canonical genera.

💡

Why this is airtight: None. Direct recall of NCERT Animal Kingdom diagnostic features.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Assigns Ctenoplana as pest and Asterias as having book lungs.

⚠️

Student Fallacy (Why candidates pick this trap): Random guessing.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Assigns scorpion as a gregarious polyphagous pest.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing predatory scorpions with herbivorous crop pests.

⚠️

NTA Trap Alert: Echinoderm Symmetry Inversion Trap

Echinoderms are the only bilateral triploblastic phylum whose adults revert to radial symmetry. Students frequently misread "adult radial, larva bilateral" and get confused.

🛡️ How to avoid the -1 mark: Remember: Asterias larva is Bilateral (ancient ancestry); Asterias adult is Radial (secondary adaptation).

📖

Core NEET Syllabus Standard

NEET / NCERT Biology · Animal Kingdom Standard Benchmark

Core Scientific Principle Tested:

"Locusta is a gregarious pest; Asterias has bilateral larvae and radial adults; scorpions possess book lungs; Ctenoplana exhibits bioluminescence."

Syllabus Focus: Classification of Animals

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2020 Botany Question 9 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ "Locusta = Pest, Asterias = Larva Bilateral / Adult Radial, Ctenoplana = Glows!"

Step-by-Step Rigorous Workflow & Mathematical Proof

Diagnostic Features and Taxonomic Alignment

Option Alignment

360° Option Elimination Engine Key Feature

NTA Trap Alert: Echinoderm Symmetry Inversion Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Animal Kingdom

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