Q54.Arrange the following animals on the basis of their phyla according to increasing level of complexity.
A. Limulus
B. Nereis
C. Taenia solium
D. Sycon
Choose the correct answer from the options given below:
(1) D, C, B, A
(2) C, D, A, B
(3) D, B, C, A
(4) C, D, B, A
The correct arrangement by phyla in increasing organizational complexity is D, C, B, A (option 1). This reflects the standard evolutionary hierarchy: Porifera (simplest cellular level) to Platyhelminthes, Annelida, then Arthropoda (most complex).
Correct Sequence
Animal complexity increases with tissue layers, body cavities, segmentation, and organ systems. Phyla order:
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D. Sycon (Phylum Porifera): Cellular/multicellular sponges; no tissues/organs, choanocytes for feeding.
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C. Taenia solium (Phylum Platyhelminthes): Acoelomate flatworms; diploblastic/triploblastic, no coelom, incomplete gut, hermaphroditic.
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B. Nereis (Phylum Annelida): Pseudocoelomate/segmented worms; true coelom, metamerism, closed circulation, setae.
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A. Limulus (Phylum Arthropoda): Ecdysozoan; exoskeleton, jointed appendages, open circulation, compound eyes, advanced nervous system.
This progression shows diploblasty → triploblasty → coelom → segmentation/chitin.
Why Other Options Fail
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Option 2 (C, D, A, B): Wrong; Platyhelminthes (C) before Porifera (D) ignores sponges’ simpler cellular organization.
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Option 3 (D, B, C, A): Wrong; Annelida (B) before Platyhelminthes (C) skips acoelomate stage to coelomate.
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Option 4 (C, D, B, A): Wrong; starts with Platyhelminthes (C), placing complex flatworms before simplest Porifera (D).
Introduction to Phyla Complexity
The arrange animals phyla increasing complexity question tests evolutionary biology basics, sequencing Sycon (Porifera), Taenia solium (Platyhelminthes), Nereis (Annelida), and Limulus (Arthropoda) by tissue, cavity, and organ sophistication—key for NEET prep.
Phyla Hierarchy Explained
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Porifera (Sycon): Simplest; porous, asymmetrical, filter-feeders.
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Platyhelminthes (Taenia solium): Flat, acoelomate, bilateral, flame cells.
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Annelida (Nereis): Segmented, coelomate, parapodia.
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Arthropoda (Limulus): Chitinous, appendages, Malpighian tubules.
NEET Exam Insights
Wrong options flip simpler phyla; memorize Porifera first, Arthropoda advanced. Links to animal kingdom classification.
Why Complexity Matters
This arrange animals phyla increasing complexity order highlights metazoan evolution, aiding biodiversity studies and exams.
