Find the correctly matched pairs

(i) Sea Urchin – parapodia

(ii) Obelia – Metagenesis

(iii) Crocodile – four-chambered heart

(iv) Lemur – thecodont

The correct answer is (ii), (iii) and (iv).

Let us analyze each pair step-by-step to determine if they are correctly matched:

(i) Sea Urchin – parapodia:
Sea urchins are marine organisms belonging to the phylum Echinodermata. They move using tube feet (podia) and spines, not parapodia. Parapodia are lateral, fleshy protuberances used for locomotion and respiration in certain aquatic annelids, such as Nereis. Therefore, this pair is incorrectly matched.

(ii) Obelia – Metagenesis:
Obelia is a genus of marine cnidarians (coelenterates). It exhibits metagenesis, which is the phenomenon of alternation of generations between an asexual, sessile polyp phase and a sexual, free-swimming medusa phase in its life cycle. Therefore, this pair is correctly matched.

(iii) Crocodile – four-chambered heart:
Most reptiles possess a three-chambered heart (consisting of two auricles and a partially divided ventricle). However, crocodilians (crocodiles, alligators, and gharials) are key exceptions in the class Reptilia, possessing a fully formed, four-chambered heart (two auricles and two ventricles). Therefore, this pair is correctly matched.

(iv) Lemur – thecodont:
Lemurs are primates belonging to the class Mammalia. Mammals characteristically exhibit thecodont dentition, a type of tooth attachment where the base of each tooth is firmly enclosed in a bony socket of the jaw. Therefore, this pair is correctly matched.

In conclusion, the correctly matched pairs are (ii), (iii), and (iv).