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Question #46402
The Question
An evolutionary biologist compares the excretory physiology of Pheretima (earthworm) and a terrestrial mammal. While both utilize tubular structures for osmoregulation, the earthworm's metanephridia are fundamentally incapable of producing a highly hypertonic urine. This physiological limitation in the earthworm is primarily due to the absence of:
Options
- A.
Active reabsorption of essential electrolytes from the filtrate.
- B.
A counter-current multiplier system coupled with a medullary interstitial gradient.
- C.
A highly coiled tubular network to maximize the surface area for secretion.
- D.
The ability to filter coelomic fluid directly into the tubular lumen.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Vasa recta|Henle's loop|Nephridia|Interstitial gradient
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often equate 'osmoregulation' and 'tubular reabsorption' directly with 'urine concentration'.
The trap assumes that any coiled excretory tube can concentrate urine.
However, the specific ability to produce hypertonic urine is a vertebrate innovation dependent strictly on the counter-current architecture and medullary gradient, not merely the presence of a reabsorptive coiled tube.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Excretory Products and Their Elimination - Class 11 |
| Concept | Protonephridia vs Metanephridia |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |