The skeleton is made entirely of cartilage in

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

Write two characteristic features of the phylum to which Ascaris belongs. Name the parasitic worm that causes elephantiasis.

Classify the following organisms based on the absence $/$ presence of true coelom,i.e.,acoelomate,pseudocoelomate,and coelomate:
$(a)$ Scorpion
$(b)$ Sea anemone
$(c)$ Ascaris
$(d)$ Earthworm
$(e)$ Wuchereria
$(f)$ Nereis

Meena and Hari observed an animal in their garden. Hari called it an insect while Meena said it was an earthworm. Choose the character from the following which confirms that it is an insect.

Explain by giving three reasons,how the work done by earlier scientists with respect to classification is helpful to the present generation.