Q.109 Botany ⭐ 360° Option Elimination Active

NEET 2025 Botany Question 109 Solution

Topic: Animal Kingdom · Official NTA Booklet Code 45

Question

While trying to find out the characteristic of a newly found animal, a researcher did the histology of adult animal and observed a cavity with presence of mesodermal tissue towards the body wall but no mesodermal tissue was observed towards the alimentary canal. What could be the possible coelome of that animal?

(1)Acoelomate
(2)Pseudocoelomate
(3)Schizocoelomate
(4)Spongocoelomate

✓

Verified Against NTA Final Answer Key

Option (2) : Pseudocoelomate

📚 Animal Kingdom Medium

📋 Given Parameters & Problem Setup

Histological Observation Cavity present between body wall and gut

Outer Lining (Body Wall) Mesodermal tissue present

Inner Lining (Alimentary Canal) No mesodermal tissue present

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The 30-Second Exam Hall Shortcut: ⚡ Coelom Lining Diagnostic

⏱️ Save ~30 seconds

True Coelom = Mesoderm on BOTH sides (body wall + gut)! Pseudocoelom = Mesoderm on body wall only (scattered pouches, gut not lined)!

1 Check mesodermal lining on both sides of the cavity:

2 True coelom (eucoelom): Mesoderm completely lines outer (somatic) AND inner (splanchnic/visceral) walls.

3 Acoelomate: No body cavity at all (mesenchyme/parenchyma fills space, e.g. Platyhelminthes).

4 Pseudocoelomate: Body cavity is derived from the blastocoel; mesoderm lines the body wall (or occurs as scattered pouches), but does NOT line the endodermal alimentary canal!

5 Therefore, the animal is a Pseudocoelomate (e.g. Aschelminthes)!

6 Select Option (2)!

🛡️

Why You Can 100% Trust This Shortcut: Diploblastic vs Triploblastic Organization & Germ Layers (NCERT Biology · Animal Kingdom).

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Definition and Embryonic Origin of Coelom Types

The body cavity between the body wall and the gut wall is a fundamental criterion for animal classification:

• Coelomates (Eucoelomates): Possess a true coelom completely lined by mesodermal epithelium (peritoneum). Somatic mesoderm lines the inner body wall, and splanchnic mesoderm surrounds the alimentary canal. Examples: Annelids, Arthropods, Molluscs, Echinoderms, Hemichordates, Chordates.
• Acoelomates: Lack any body cavity; space between gut and body wall is filled with mesodermal parenchyma tissue. Example: Platyhelminthes.
• Pseudocoelomates: The body cavity is not completely lined by mesoderm. Instead, mesoderm is present only towards the body wall (or as scattered pouches between ectoderm and endoderm), and the endodermal alimentary canal has no surrounding mesodermal tissue. Example: Aschelminthes (roundworms).

Step 2

Matching the Histological Observation

The researcher observes: mesoderm towards the body wall, but NO mesodermal tissue towards the alimentary canal. This precisely describes a false coelom or pseudocoelom, which persists from the embryonic blastocoel without developing a visceral peritoneum around the gut.

Step 3

Conclusion

The coelome of this newly found animal is a pseudocoel, and the organism is classified as a Pseudocoelomate.

\text{Lining on Body Wall only (No Gut Lining)} \implies \text{Pseudocoelomate}

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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 A

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Acoelomates have no cavity whatsoever between the body wall and gut wall.

⚠️

Student Fallacy (Why candidates pick this trap): Ignoring the observed cavity in the histological section.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

100% correct. In pseudocoelomates, mesoderm is present on the outer body wall side but does not enclose the gut.

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Why this is airtight: None; rigorous embryological understanding.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Schizocoelomates (annelids, arthropods, molluscs) possess a true coelom formed by splitting of mesoderm, lined by mesoderm on BOTH body wall and gut.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing the mechanism of true coelom formation with incomplete mesodermal lining.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. "Spongocoelomate" is a spurious non-biological term; sponges have a spongocoel / paragastric cavity, not a coelom.

⚠️

Student Fallacy (Why candidates pick this trap): Distracted by fabricated terminology.

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NTA Trap Alert: Scattered Pouches vs One-Sided Mesoderm Description

NCERT often describes pseudocoelom as having "mesoderm present as scattered pouches between ectoderm and endoderm". Here the question tests the anatomical consequence: mesoderm covers body wall, but not the gut tube. Do not get confused if the wording varies from "scattered pouches"!

🛡️ How to avoid the -1 mark: If the cavity lacks a mesodermal lining over the gut, it CANNOT be a true coelom; it is a pseudocoelom.

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Core NEET Syllabus Standard

NEET Biology Core Syllabus · Animal Kingdom Standard Benchmark

Core Scientific Principle Tested:

"In pseudocoelomates, the body cavity is not lined by mesoderm; mesoderm is present only towards the body wall or as pouches, leaving the alimentary canal unlined by mesoderm."

Syllabus Focus: Basis of Classification · Coelom

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

PSEUDO = Partial/Phony lining (Lines Body wall, skips Gut)!

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NEET 2025 Botany Question 109 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Coelom Lining Diagnostic

Step-by-Step Rigorous Workflow & Mathematical Proof

Definition and Embryonic Origin of Coelom Types

Matching the Histological Observation

Conclusion

360° Option Elimination Engine Key Feature

NTA Trap Alert: Scattered Pouches vs One-Sided Mesoderm Description

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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