Regulation and coordination by cells = $P$
Regulation and coordination by chemicals = $Q$
Select the correct option for $P$ and $Q$.
$\quad\quad \quad P\quad\quad\quad Q$

Explain the following:
$(a)$ Role of $Na ^{+}$ in the generation of action potential
$(b)$ Mechanism of generation of light-induced impulse in the retina.
$(c)$ Mechanism through which a sound produces a nerve impulse in the inner ear.

Select the mixed type of cranial nerves from the following list:
$i$. Pathetic (Trochlear)
$ii$. Trigeminal
$iii$. Facial
$iv$. Auditory (Vestibulocochlear)
$v$. Glossopharyngeal

Which of the following is an odd nerve?

Differentiate between: (Any four)
$(a)$ Myelinated and non-myelinated axons
$(b)$ Dendrites and axons
$(c)$ Rods and cones
$(d)$ Thalamus and Hypothalamus
$(e)$ Cerebrum and Cerebellum

Read the following statements:
$(A)$ The neural system provides an organized network for point-to-point connections.
$(B)$ The endocrine system provides chemical integration through hormones.
$(C)$ The neural system is very simple in lower invertebrates.
$(D)$ Neurons can detect and receive stimuli but cannot conduct them.
How many of the above statements are incorrect?