Answer: It refers to alternation between asexual polyp and sexual medusa forms within the life cycle.
- A It refers to alternation between asexual polyp and sexual medusa forms within the life cycle
- B It refers to the formation of a water vascular system used for locomotion in echinoderms
- C It is a type of asexual budding and fragmentation seen exclusively in sponges
- D It describes the alternation between haploid gametophyte and diploid sporophyte plant generations
Correct answer: A. It refers to alternation between asexual polyp and sexual medusa forms within the life cycle
Explanation: Metagenesis in cnidarians like Obelia refers to the alternation between the asexual, sessile polyp form and the sexual, free-swimming medusa form within a single life cycle.
Moving across the animal phyla, body organisation becomes progressively more complex: from no symmetry and cellular organisation (Porifera) through radial/diploblastic (Cnidaria), bilateral/acoelomate (Platyhelminthes), pseudocoelomate (Nematoda), to a true coelom with full organ systems (Annelida and beyond).
Concept context
Phylum-level classification of the animal kingdom from Porifera to Chordata, based on body symmetry, coelom, and segmentation. One of the most example-heavy chapters for NEET.