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Question #46120
The Question
Metamerism is a fundamental body plan feature in Annelida, Arthropoda, and Chordata, requiring precise temporal and directional segment formation during embryogeny. Which of the following statements regarding the establishment and nature of segmentation is INCORRECT?
Options
- A.
In earthworms, true metamerism involves the sequential addition of segments from a posterior growth zone, establishing repeating neuromuscular units.
- B.
In chordates, the temporal disruption of embryonic somitogenesis prevents the establishment of a serially repeated axial skeleton and myotomes.
- C.
In pseudometameric flatworms like Taenia, new segments are generated from a posterior growth zone, pushing older mature segments anteriorly.
- D.
True metamerism exhibits interdependent physiological integration among segments, whereas pseudometameric proglottids function as largely independent reproductive units.
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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
Embryogeny_Directionality|Metamerism|Animal_Kingdom
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Embryogeny directionality and the anatomical location of segment addition.
Students often conflate the growth mechanism of true metamerism (posterior addition in annelids) with pseudometamerism, assuming all 'segmented' worms grow from the tail.
This is a classic 'Location/Directionality Trap' testing the precise NCERT distinction between true metameric growth and tapeworm strobilation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Animal Kingdom - Class 11 |
| Concept | Segmentation vs. Metamerism |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |