Which of the following is/are controlled by the human brain?
$(a)$. Balance of the body
$(b)$. Circadian rhythm of the body
$(c)$. Human behaviour
$(d)$. Functioning of heart and kidneys

Which of the following cranial nerves are classified as mixed nerves?

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

Which of the following statements are correct?
$(i)$ $Ramus$ $dorsalis$ branch of spinal nerve contains sensory as well as motor nerve fibres.
(ii) The preganglionic nerve fibres arise from the entire spinal cord.
(iii) There are $31$ pairs of spinal nerves.
(iv) The somatic nervous system transmits impulses from $CNS$ to visceral organs.
$(v)$ Reflex action is a sudden,thoughtful,and voluntary response to the applied stimulus.
Select the correct option.

Identify the location and function of the following structures:
$(1)$ Cone cells
$(2)$ Ear ossicles

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.