Cutaneous stimulus is received by

The nervous system in vertebrates develops from which of the following germ layers?

Proprioceptors are those,which give the sense of

The olfactory nerve is the .... cranial nerve.

Arrange the following in the correct sequence in the evolution of the nervous system:
$(a)$ Formation of a centralised nervous system.
$(b)$ Diffused nervous system in $Hydra$.
$(c)$ Formation of a ganglion.
$(d)$ Nervous system is lacking in sponges.

In Hydra,neural organization is comprised of: