Why do we classify both snakes and turtles in the same class?

Identify a member of the phylum Porifera.

In which group of animals is the coelom filled with blood?

Give examples for the following:
$(a)$ Bilateral,dorsiventral symmetry is found in ...............
$(b)$ Worms causing disease elephantiasis is ..............
$(c)$ Open circulatory system is found in ............. where coelomic cavity is filled with blood.
$(d)$ ............... are known to have pseudocoelom.

$(a)$ State two characteristic features of nematodes.
$(b)$ Identify the phylum with the help of the following features:
$(i)$ Spiny-skinned,radially symmetrical,and have tube feet.
$(ii)$ Triploblastic,worm-like,having a segmented body.

Draw the diagram of $Spirogyra$ and label the following parts:
$(a)$ Cell wall $(b)$ Pyrenoid $(c)$ Nucleus $(d)$ Chloroplast.