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Question #46401
The Question
A comparative analysis of excretory fluid dynamics reveals stark differences between the protonephridia of Planaria and the metanephric kidneys of mammals. Which of the following statements is INCORRECT regarding these physiological mechanisms?
Options
- A.
Protonephridia are primarily concerned with ionic and fluid volume regulation, whereas mammalian kidneys are heavily adapted for both osmoregulation and nitrogenous waste excretion.
- B.
Fluid entry into the protonephridial network is driven by negative pressure generated by ciliary beating, unlike the positive hydrostatic pressure driving mammalian glomerular filtration.
- C.
To prevent nutrient loss, protonephridia utilize a high-pressure ultrafiltration mechanism that establishes a distinct 'renal threshold' for glucose, analogous to the mammalian proximal convoluted tubule.
- D.
The excretory fluid in Planaria is derived directly from the interstitial space rather than blood plasma, rendering the concept of a 'tubular maximum' physiologically inapplicable.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Flame cells|Renal threshold|Glucose|Tubular secretion
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often conflate the generalized term 'filtration' in primitive organisms with the specific 'high-pressure ultrafiltration' of vertebrate GFR.
The trap exploits the assumption that all excretory tubules must possess a 'renal threshold' to prevent nutrient loss, failing to realize that this concept strictly depends on the saturation of transport proteins following massive, pressure-driven plasma filtration—a mechanism entirely absent in acoelomate flatworms.
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 |