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Question #46103
The Question
The evolutionary transition to bilateral symmetry is generally accompanied by cephalization. However, Phylum Echinodermata presents a unique evolutionary trajectory. Which of the following statements regarding the symmetry and nervous organization of Echinoderms is INCORRECT?
Options
- A.
The presence of bilateral symmetry in their larval stages indicates a phylogenetic descent from a bilaterally symmetrical common ancestor.
- B.
The transition from a bilateral larva to a radially symmetrical adult is termed secondary radiality, an adaptation often associated with a slow-moving benthic lifestyle.
- C.
Despite the loss of bilateral symmetry, adult echinoderms retain a centralized cephalic nerve ring to coordinate their complex water vascular system.
- D.
The absence of cephalization in adult echinoderms demonstrates that the operation of complex organ systems does not strictly require centralized brain control.
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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
Radial_Symmetry|Bilateral_Symmetry|Echinodermata|Cephalization
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often associate 'complex organ systems' (like the water vascular system) with a 'centralized brain', or assume that because echinoderms are advanced Deuterostomes, they must retain some cephalization.
The trap relies on Functional Overlap and Terminology; students remember echinoderms have a 'nerve ring' and gloss over the word 'cephalic', missing the fundamental rule that radial symmetry in these adults is accompanied by a complete evolutionary regression of cephalization.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Animal Kingdom - Class 11 |
| Concept | Symmetry and Cephalization correlation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |