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Question #46108
The Question
The transition from an acoelomate to a pseudocoelomate body plan in Aschelminthes introduces a fluid-filled cavity derived from the embryonic blastocoel. Based on the specific anatomical arrangement of their germ layers, which of the following represents the most significant functional constraint of this body plan when compared to eucoelomates?
Options
- A.
Direct mixing of the pseudocoelomic fluid with digestive enzymes, preventing efficient extracellular digestion.
- B.
Absence of a mesodermally derived muscular layer around the intestine, limiting independent peristaltic movements of the gut.
- C.
Inability to develop a muscular pharynx, as the scattered mesodermal pouches cannot support anterior gut differentiation.
- D.
Failure of the persistent blastocoel to function as a hydrostatic skeleton, restricting them exclusively to a parasitic mode of life.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Aschelminthes|Blastocoel_Persistence|Mesoderm_Distribution
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the NCERT line 'mesoderm is present as scattered pouches' without synthesizing its anatomical consequence.
The trap lies in confusing the NCERT fact that Aschelminthes have a 'well-developed muscular pharynx' with the assumption that their entire gut is muscular.
The lack of a mesodermal lining specifically on the endoderm means the intestine itself cannot undergo independent peristalsis, a key evolutionary leap achieved later by true coelomates (eucoelomates).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Animal Kingdom - Class 11 |
| Concept | Coelom Categorization |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |