Distinguish between :
(a) afferent neurons and efferent neurons
(b) impulse conduction in an myelinated nerve fibre and unmyelinated nerve fibre
(c ) aqueous humour and vitreous humor
(d) blind spot and yellow spot
(f) cranial nerves and spinal nerves .

Assertion:Myelinated nerve fibres are present in spinal and cranial nerves. Reason:Myelinated nerves conduct impulses more radidly than unmyelinated nerves.

Read the given statements and select the correct option. (i)Synaptic cleft of neurons secreates adrenaline. (ii)Myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon. (iii)Non-myelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath. (iv)Spinal and cranial nerves are made of non-myelinated nerve fibres.

The region of the vertebrate eye, where the optic nerve passes out of the retina, is called the (a) fovea (b) iris (c ) blind spot (d) optic chaisma

Assertion:Reflex arc comprises of at least one afferent neuron, one efferent neuron and a part of PNS. Reason:The efferent neuron receivers signal from a sensory organ and transmits the impulse via a ventral nerve root into the PNS.

Explain the following processes: (a) Polarisation of the membrane of a nerve fibre. (b) Depolaristion of the membrance of a nerve fibre. (c ) Conduction of nerver impulse along a nerve fibre. (d) Transmission of a nerve impulse across a chemical synapse.

Read the given paragraph about human eye carefully and correct the mistakes. Our eye is cylindrical shaped. The wall of the eyeball is composed of five layers.The outermost layer is cornea. The innermost layer is called sclera. The eyeball consists of elastic nerves and biconcave lens.The pupil attaches lens to iris . Iris has rod and cone shaped cells. Aqueous humour is present between lens and retina. The vitreous humour is present between cornea and lens . The brain changes the light into nerve impulses and sends them to retina.

Identify the correct statement from the below. (I) The repeatedly branched short fibres coming out of the cell body are called dendrites. (II) the cell body and the dendrites contain neurons. (lII) An axon is along that arises from a cone shaped area of the cell body called teh Axon hillock (IV) Axon hillock is the place where the nerve impulse is generated in the motor neurons.