Question

Which of the following statements are incorrect?
(i) When an impulse travels along a myelinated 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 transit impulses.

• A. (i), (ii) and (iv)
• B. (ii) and (iv)
• C. (ii) and (iii)
• D. (i), (iii) and (v)

Answer 1

The correct option is C (ii) and (iii)

At chemical synapse, one neuron sends a message to a target neuron - another cell. An action potential triggers the presynaptic neuron to release neurotransmitters. These molecule bind to the receptors on the postsynaptic cell and make it more or less likely to fire an action potential.

Neurotransmitter are chemical messengers that transmit a message from a nerve cell across the synapse to a target cell. They are chemicals made by the nerve cell specifically to transmit the message.

So, option C is the correct option.