Nematocysts take part in

Which of the following animals possesses neurons but lacks a nervous system (nerve net/ganglia/brain)?

Radial symmetry is observed in:

Which one of the following living organisms completely lacks a cell wall?

Which phylum consists of animals with radial symmetry?

Identify the correct features for $Medusa$ and $Polyp$ forms in Phylum $Coelenterata$ (Cnidaria) from the given list:
$I$ - $Sessile$
$II$ - $Umbrella-shaped$
$III$ - $Free-swimming$
$IV$ - $Produced$ $by$ $asexual$ $reproduction$
$V$ - $Cylindrical$
$VI$ - $Produced$ $by$ $sexual$ $reproduction$
$Medusa$ $\quad\quad$ $Polyp$