Q.87 Zoology ⭐ 360° Option Elimination Active

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NEET 2020 Zoology Question 87 Solution

Topic: Animal Kingdom · Official NTA Booklet Code E1

Question

Bilaterally symmetrical and acoelomate animals are exemplified by:

(1)Ctenophora
(2)Platyhelminthes
(3)Aschelminthes
(4)Annelida

✓

Verified Against NTA Final Answer Key

Option (2) : Platyhelminthes

📚 Animal Kingdom Easy

📋 Given Parameters & Problem Setup

Symmetry Bilateral symmetry

Body Cavity (Coelom) Acoelomate (solid mesenchyme / parenchyma, no coelom)

Question Objective Identify the phylum exhibiting both diagnostic criteria

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The 30-Second Exam Hall Shortcut: ⚡ "Platyhelminthes = Triploblastic, Bilateral & ACOELOMATE Flatworms!"

⏱️ 20 seconds

Ctenophora are radially symmetrical and diploblastic. Aschelminthes (roundworms) are Pseudocoelomates. Annelida are true Eucoelomates. Platyhelminthes (flatworms) are the ONLY bilaterally symmetrical ACOELOMATE animals! Mark Platyhelminthes (Option 2) in 5 seconds.

1 Ctenophores: Radial symmetry, acoelomate, diploblastic.

2 Platyhelminthes: Bilateral symmetry, triploblastic, acoelomate.

3 Aschelminthes: Bilateral symmetry, triploblastic, pseudocoelomate.

4 Annelids: Bilateral symmetry, triploblastic, coelomate (eucoelomate).

5 Select Option (2) Platyhelminthes.

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Animal Kingdom (Basis of Classification: Coelom & Phylum Platyhelminthes)

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Review Body Cavity Classification

Animals in which the body cavity is absent and the mesoderm forms a solid packing tissue (parenchyma) between the ectoderm and gut wall are called acoelomates.

Step 2

Review Body Symmetry

In bilateral symmetry, the body can be divided into identical left and right halves in only one plane.

Step 3

Map Phyla Against Both Criteria

- Platyhelminthes (Flatworms): Triploblastic, bilaterally symmetrical, and acoelomate (NCERT verbatim: "acoelomates, e.g., Platyhelminthes"). - Aschelminthes: Bilaterally symmetrical, but PSEUDOCOELOMATE. - Annelida: Bilaterally symmetrical, but TRUE COELOMATE (schizocoelomate). - Ctenophora: Radially symmetrical and diploblastic.

Step 4

Conclude Platyhelminthes

Platyhelminthes uniquely satisfies both conditions of being bilaterally symmetrical and acoelomate.

⭐

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; Ctenophores exhibit radial (or biradial) symmetry and are diploblastic acoelomates, lacking bilateral symmetry.

⚠️

Student Fallacy (Why candidates pick this trap): Overlooking the bilateral symmetry requirement.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

Factually exact; flatworms are the sole triploblastic bilaterally symmetrical animals that are acoelomate.

💡

Why this is airtight: None; core animal kingdom classification hallmark.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect; Aschelminthes are pseudocoelomates with persistent blastocoel, not acoelomates.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing pseudocoelomate (Aschelminthes) with acoelomate (Platyhelminthes).

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect; Annelids possess a true coelom lined by mesoderm (schizocoelomates).

⚠️

Student Fallacy (Why candidates pick this trap): Assuming coelomate annelids are acoelomates.

⚠️

NTA Trap Alert: Coelom Types Sequence in Animal Kingdom

Porifera, Coelenterata, Ctenophora, Platyhelminthes = ACOELOMATE. Aschelminthes = PSEUDOCOELOMATE. Annelida to Chordata = COELOMATE (Eucoelomate).

🛡️ How to avoid the -1 mark: Only ONE bilaterally symmetrical phylum is acoelomate: PLATYHELMINTHES!

📖

Core NEET Syllabus Standard

Zoology · Animal Kingdom Standard Benchmark

Core Scientific Principle Tested:

Syllabus Focus: Body Symmetry and Coelom: Bilateral Symmetry & Acoelomate in Platyhelminthes

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2020 Zoology Question 87 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ "Platyhelminthes = Triploblastic, Bilateral & ACOELOMATE Flatworms!"

Step-by-Step Rigorous Workflow & Mathematical Proof

Review Body Cavity Classification

Review Body Symmetry

Map Phyla Against Both Criteria

Conclude Platyhelminthes

360° Option Elimination Engine Key Feature

NTA Trap Alert: Coelom Types Sequence in Animal Kingdom

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Animal Kingdom

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Fundamental Diagnostic Characteristics of Phylum Chordata

Coelom Types and Mesodermal Linings (Pseudocoelomate)

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