Which of the following phyla is characterised by radial symmetry, diploblastic organisation and the presence of cnidoblasts?
A{'text': 'Coelenterata', 'label': 'A'}
B{'text': 'Porifera', 'label': 'B'}
C{'text': 'Ctenophora', 'label': 'C'}
D{'text': 'Platyhelminthes', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'Coelenterata', 'label': 'A'}
1. Radial symmetry appears in Coelenterata, Ctenophora and Echinodermata.
2. Diploblastic organisation with ectoderm + endoderm is exclusive to Coelenterata and Ctenophora.
3. Cnidoblasts (cnidocytes containing nematocysts) are diagnostic of Coelenterata (Cnidaria) alone.
4. Ctenophores use ciliated comb plates and lack cnidoblasts.
_Source: NCERT Class 11 Biology, Ch 4 "Animal Kingdom", §4.2.2_
Related questions
Which pair of features is characteristic of phylum Aschelminthes?An animal has a body plan that is diploblastic, radially symmetrical and lacks a coelom. TThe circulatory system in insects and other arthropods is best described asWhich of the following is NOT correctly matched with its phylum?Cnidarians that exhibit polyp and medusa alternating in the life cycle (Metagenesis) incluIn sponges the cells lining the spongocoel and canals areThe correct sequence of increasing organisational complexity in Animalia isBioluminescence — the ability of a living organism to emit light — is well-marked in membe