question_answer

Which of the following statements are incorrect?

(i) When an impulse travels along a myelin sheath neuron, it leaps over the myelin sheath from one node to the next.

(ii) At chemical synapse there is continuity between the presynaptic and postsynaptic neurons provided by the gap junctions.

(iii) Neurotransmitters are chemicals that are released from postsynaptic neuron which interact with specific receptors of presynaptic neuron.

(iv) Neurons releasing acetylcholine are described as cholinergic neurons and those releasing noradrenaline are described as adrenergic neurons.

(v) Refractory period is the period after the transmission of an impulse in a nerve fibre in which membrane of the axon regains its ability to transmit impulses.

A)  (i), (ii) and (v) 

B)         (ii) and (iv)    

C)  (ii) and (iii)     

D)  (i), (iii) and (v)