Q.197 Zoology ⭐ 360° Option Elimination Active

NEET 2021 Zoology Question 197 Solution

Topic: Organisms and Populations · Official NTA Booklet Code M1

Question

Match List - I with List - II. (a) Allen's Rule (i) Kangaroo rat (b) Physiological adaptation (ii) Desert lizard (c) Behavioural adaptation (iii) Marine fish at depth (d) Biochemical adaptation (iv) Polar seal List - I List - II Choose the correct answer from the options given below. (a) (b) (c) (d)

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

✓

Verified Against NTA Final Answer Key

Option (3) : (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)

📚 Organisms and Populations Medium

📋 Given Parameters & Problem Setup

List I (Adaptation Rules / Classes) (a) Allen's Rule, (b) Physiological adaptation, (c) Behavioural adaptation, (d) Biochemical adaptation

List II (Organisms) (i) Kangaroo rat, (ii) Desert lizard, (iii) Marine fish at depth, (iv) Polar seal

⚡

The 30-Second Exam Hall Shortcut: ⚡ "Allen's Rule = Polar Seal, Behavioural = Desert Lizard, Physiological = Kangaroo Rat"

⏱️ Save ~30 seconds

Allen's rule states cold-climate mammals have shorter extremities, exemplified by polar seals with short flippers & blubber ((a)-(iv)). Desert lizards regulate body temperature purely through behaviour by basking in sun and moving to shade ((c)-(ii)). Kangaroo rat concentrates urine and oxidizes fat physiologically ((b)-(i)). Marine fish survive crushing deep pressure biochemically ((d)-(iii)). Match is (iv), (i), (ii), (iii) -> Option (3)!

1 Match (a) Allen's Rule -> (iv) Polar seal (blubber and reduced extremities to prevent heat loss).

2 Match (b) Physiological adaptation -> (i) Kangaroo rat (internal fat oxidation for metabolic water and hyper-concentrated urine).

3 Match (c) Behavioural adaptation -> (ii) Desert lizard (basks in sun when cold, retreats to shade/burrows when hot).

4 Match (d) Biochemical adaptation -> (iii) Marine fish at depth (specialized enzymes and pressure-resistant biochemical machinery).

5 Match pattern (iv), (i), (ii), (iii) -> Option (3).

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Organisms and Populations (Adaptations: Mammals from colder climates generally have shorter ears and limbs to minimise heat loss (Allen’s Rule) - seal in polar seas; Kangaroo rat in North American deserts can meet all water requirements through internal fat oxidation; Desert lizards lack physiological regulation and manage body temperature behaviourally; Marine invertebrates and fish thrive at great ocean depths through biochemical adaptations).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Analysis of Each Adaptation Class and Classic NCERT Type Specimen

- (a) Allen’s Rule: Formulated by Joel Asaph Allen: Mammals from colder climates generally possess shorter ears, limbs, and extremities to minimize surface area-to-volume ratio and reduce conductive heat loss. In polar seas, aquatic mammals like the polar seal exhibit shortened flippers and an insulating subcutaneous fat layer (blubber). - (b) Physiological Adaptation: The Kangaroo rat (*Dipodomys*) of North American deserts is capable of living without drinking liquid water: it fulfills 90% of its water requirements via the endogenous physiological oxidation of internal storage fat (producing metabolic water) and possesses elongated loops of Henle that concentrate its urine to hyperosmolar levels. - (c) Behavioural Adaptation: Desert lizards lack the internal physiological capacity for autonomic thermoregulation (homeothermy). Instead, they manage body temperature behaviourally: they bask in the morning sun to absorb solar radiation when body temperature drops below comfort zone, and scurry into subterranean burrows or shaded crevices when ambient temperatures climb. - (d) Biochemical Adaptation: Organisms living in extreme marine abyssal depths (where hydrostatic pressure exceeds 100 atmospheres) possess biochemical adaptations, including piezolyte pressure-protecting osmolytes (TMAO) and specialized membrane unsaturations that keep membranes fluid and enzymes functional under immense hydrostatic crush forces.

\begin{aligned} \text{Allen's Rule} &\iff \text{Polar seal} \quad [\text{(a)} \to \text{(iv)}] \\ \text{Physiological adaptation} &\iff \text{Kangaroo rat} \quad [\text{(b)} \to \text{(i)}] \\ \text{Behavioural adaptation} &\iff \text{Desert lizard} \quad [\text{(c)} \to \text{(ii)}] \\ \text{Biochemical adaptation} &\iff \text{Marine fish at depth} \quad [\text{(d)} \to \text{(iii)}] \end{aligned}

Step 2

Option Alignment and Conclusion

Sequence of matches: (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii). This corresponds uniquely to Option (3).

⭐

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 1

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Assigns physiological adaptation to desert lizard and biochemical adaptation to kangaroo rat.

⚠️

Student Fallacy (Why candidates pick this trap): Swapping behavioural adaptation with physiological/biochemical categories.

2 2

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Misidentifies marine fish as behavioural and desert lizard as biochemical.

⚠️

Student Fallacy (Why candidates pick this trap): Failing to remember that desert lizards regulate body temperature behaviourally.

3 3

✓ 100% Correct

Verdict & Scientific Reason:

Correct. Flawlessly aligns all 4 adaptation classes with their canonical NCERT textbook examples.

💡

Why this is airtight: None. Candidate accurately connects each adaptation mechanism.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Assigns marine fish to physiological and kangaroo rat to biochemical adaptation.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing internal physiological water retention with deep ocean pressure biochemistry.

⚠️

NTA Trap Alert: Physiological vs Behavioural Desert Adaptation Trap

Both the kangaroo rat and the desert lizard live in hot, arid deserts. The critical distinction is that the kangaroo rat adapts *physiologically* (fat oxidation and renal urine concentration), whereas the desert lizard adapts *behaviourally* (basking in sun vs moving to shade).

🛡️ How to avoid the -1 mark: Remember: Lizard = Basking Behaviour; Kangaroo rat = Internal Metabolic Physiology.

📖

Core NEET Syllabus Standard

NEET / NCERT Biology · Organisms and Populations Standard Benchmark

Core Scientific Principle Tested:

"Polar seal illustrates Allen’s rule; kangaroo rat exhibits physiological adaptation; desert lizard exhibits behavioural adaptation; deep marine fish exhibit biochemical adaptation."

Syllabus Focus: Adaptations

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2021 Zoology Question 197 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ "Allen's Rule = Polar Seal, Behavioural = Desert Lizard, Physiological = Kangaroo Rat"

Step-by-Step Rigorous Workflow & Mathematical Proof

Analysis of Each Adaptation Class and Classic NCERT Type Specimen

Option Alignment and Conclusion

360° Option Elimination Engine Key Feature

NTA Trap Alert: Physiological vs Behavioural Desert Adaptation Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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