Animals possess nerve networks or nervous systems to respond to their environment. But
the single celled Amoeba does not possesses any nerve cell, so, how it come to know
whether a particle it encounters is a grain of sand and not its dinner?
(1) By chemotaxis
(2) By skin
(3) By hormones
(4) All of these
Assertion : Circular smooth muscles of iris contract when bright light falls on the eye.
Reason : Pupil gets constricted by the contraction of circular smooth muscles of iris.
Assertion : Tongue is a gustatoreceptor.
Reason : Receptors for gustatory sensations are located in the taste bund.
Assertion : All of the cranial nerves are said to be mixed nerves.
Reason : All cranial nerves carry both sensory and motor nerve fibres simultaneously.
Assertion : The chemical stored in the synaptic vesicles are termed as neurotransmitters.
Reason : Synaptic vesicles release these chemicals in the synaptic cleft.
Assertion : Nerve impulse can never be transmitted from dendrite or cell body of one neuron to the axon of the next neuron, across a synapse.
Reason : This happens because of the synaptic delay at each synapse.
Assertion : Nerve conduction is the one way conduction.
Reason : Nerve impulse is transmitted from dendrite terminals to axon terminals.
Assertion : After hearing a sound, nerve impulse passes from neurons to the brain.
Reason : The neurons which pass nerve impulses from the body organ to the brain is called afferent neuron.
Assertion : Cerebrospinal fluid is present throughout the central nervous system.
Reason : CSF has no such function.
Assertion : A person has lost most of its intelligence, memory and judgement.
Reason : A person has operated a tumour located in the cerebrum.