Q.172 Zoology ⭐ 360° Option Elimination Active

NEET 2026 Zoology Question 172 Solution

Topic: Organisms and Populations · Official NTA Booklet Code 50

Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Abingdon tortoise in Galapagos islands became extinct within a decade after goats were introduced. Reason R: Goats were more efficient at browsing than Abingdon tortoise. In the light of the above statements, choose the most appropriate answer from the options given below:

(1)Both A and R are correct and R is the correct explanation of A
(2)Both A and R are correct but R is not the correct explanation of A
(3)A is correct but R is not correct
(4)A is not correct but R is correct

✓

Verified Against NTA Final Answer Key

Option (1) : Both (A) and (R) are true and (R) is the correct explanation of (A)

📚 Organisms and Populations Easy

📋 Given Parameters & Problem Setup

Assertion (A) The Abingdon tortoise in Galapagos Islands became extinct within a decade after goats were introduced on the island.

Reason (R) Goats had greater browsing efficiency than the tortoises for the available resources.

⚡

The 30-Second Exam Hall Shortcut: ⚡ Competitive Exclusion "Because" Link

⏱️ Save ~35 seconds

Tortoises went extinct BECAUSE goats were faster and more efficient browsers!

1 Read Assertion (A): Abingdon tortoise in Galapagos became extinct within a decade after goats were introduced -> TRUE (NCERT verbatim).

2 Read Reason (R): Goats had greater browsing efficiency than tortoises -> TRUE (NCERT verbatim).

3 Apply the "BECAUSE" connector: The Abingdon tortoise went extinct within a decade BECAUSE introduced goats had vastly greater browsing efficiency, rapidly consuming the available vegetation and competitively starving the slow-moving tortoises.

4 Reason (R) gives the precise biological cause for Assertion (A).

5 Select Option (1) with absolute confidence.

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Organisms and Populations (Predation & Camouflage: Monarch butterfly unpalatable to predatory birds).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Evaluate Assertion (A)

Competition is best defined as a process in which the fitness of one species is significantly lower in the presence of another species. A classic ecological example documented in NCERT is the Abingdon tortoise in Galapagos Islands, which became extinct within a decade after goats were introduced on the island.

\text{Introduction of Goats} \xrightarrow{\text{Interspecific Competition}} \text{Extinction of Abingdon Tortoise (Within 10 Years)}

• Assertion (A) is completely true.

Step 2

Evaluate Reason (R) and Explanatory Link

Goats are agile, fast-eating herbivores with greater browsing efficiency than the slow-moving, ectothermic Abingdon tortoises. Goats outcompeted the tortoises for scarce island vegetation, driving them to extinction. Thus, Reason (R) is true and perfectly explains Assertion (A).

\text{Browsing Efficiency: Goats} \gg \text{Tortoises} \implies \text{Competitive Exclusion} \implies (R) \text{ explains } (A)

• Illustrates Gause’s Principle of Competitive Exclusion in nature.

⭐

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:

100% correct. The greater browsing efficiency of goats is the direct reason the tortoises were competitively eliminated.

💡

Why this is airtight: None; verbatim NCERT explanation.

2 B

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Reason (R) directly explains the cause of extinction in Assertion (A).

⚠️

Student Fallacy (Why candidates pick this trap): Failing to link resource competition to extinction.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Reason (R) is a documented empirical fact.

⚠️

Student Fallacy (Why candidates pick this trap): Assuming tortoises were better browsers.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Assertion (A) is a historic ecological extinction event.

⚠️

Student Fallacy (Why candidates pick this trap): Thinking Abingdon tortoises are still thriving.

⚠️

NTA Trap Alert: Predation vs. Competition Confusion

Students sometimes mistakenly think goats "preyed upon" or attacked the tortoises. Goats are herbivores; the interaction was purely interspecific COMPETITION for food.

🛡️ How to avoid the -1 mark: Remember: Goats ate the grass, NOT the tortoises (Exploitative Competition).

📖

Core NEET Syllabus Standard

NEET Biology Core Syllabus · Organisms and Populations Standard Benchmark

Core Scientific Principle Tested:

"The Abingdon tortoise in Galapagos became extinct after goats were introduced due to the greater browsing efficiency of the goats."

Syllabus Focus: Interspecific Competition

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Goats Gulp Grass Faster = Tortoises Terminated!

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NEET 2026 Zoology Question 172 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Competitive Exclusion "Because" Link

Step-by-Step Rigorous Workflow & Mathematical Proof

Evaluate Assertion (A)

Evaluate Reason (R) and Explanatory Link

360° Option Elimination Engine Key Feature

NTA Trap Alert: Predation vs. Competition Confusion

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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