$I.Q.$ is the ratio of mental age to

Which of the following systems are involved in the regulation and coordination of the human body?
$I -$ Digestive system
$II -$ Endocrine system
$III -$ Excretory system
$IV -$ Nervous system
$V -$ Reproductive system

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

The stimuli of hunger,thirst,blood pressure,and body balance are received by the:

In Hydra,neural organization is comprised of:

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.