The correct sequence of increasing organisational complexity in Animalia is
A{'text': 'Cellular → Tissue → Organ → Organ-system', 'label': 'A'}
B{'text': 'Cellular → Organ → Tissue → Organ-system', 'label': 'B'}
C{'text': 'Tissue → Cellular → Organ-system → Organ', 'label': 'C'}
D{'text': 'Organ → Tissue → Cellular → Organ-system', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'Cellular → Tissue → Organ → Organ-system', 'label': 'A'}
1. Sponges show cellular level of organisation (loose cell aggregates).
2. Coelenterates and Ctenophores show tissue level of organisation.
3. Platyhelminthes and higher phyla up to Aschelminthes are broadly at organ level.
4. Annelids and above (arthropods, molluscs, chordates) exhibit organ-system level.
_Source: NCERT Class 11 Biology, Ch 4 "Animal Kingdom", §4.1.1_
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