Justify giving one reason: crocodiles have a four-chambered heart,but are still classified as reptiles.

State the reason for the following:
$(i)$ Nematodes have a pseudocoelom.
$(ii)$ Arthropods have an open circulatory system.
$(iii)$ Echinoderms are named as such.

Associate the following features with the groups in which they first appeared:
$(a)$ Vascular tissues
$(b)$ Notochord
$(c)$ Seeds inside fruits

Which among the following have an open circulatory system?
$(i)$ Arthropoda
$(ii)$ Mollusca
$(iii)$ Annelida
$(iv)$ Coelenterata

Give reasons for the following:
$(i)$ Bryophytes are called amphibians of the plant kingdom.
$(ii)$ From phylum Platyhelminthes onwards,animals are categorized as 'triploblastic.'
$(iii)$ The presence of 'coelom' in an animal's body is considered advantageous.

Which among the following have scales?
$(i)$ Amphibians
$(ii)$ Pisces
$(iii)$ Reptiles
$(iv)$ Mammals