Select the incorrect statement regarding synapses :
- The membranes of presynaptic and postsynaptic neurons are in close proximity in an electrical synapse.
- Electrical current can flow directly from one neuron into the other across the electrical synapse.
- Chemical synapses use neurotransmitters.
- Impulse transmission across a chemical synapse is always faster than that across an electrical synapse.
Answer
(4) Impulse transmission across a chemical synapse is always faster than that across an electrical synapse.
Solution
As per NCERT, at electrical synapses the membranes of pre- and post-synaptic neurons are in very close proximity, and electrical current can flow directly from one neuron into the other, so (1) and (2) are correct.
At a chemical synapse, chemicals called neurotransmitters carry the impulse across the synaptic cleft, so (3) is correct.
NCERT also states that impulse transmission across an electrical synapse is always faster than that across a chemical synapse.
∴ Statement (4) is incorrect.
Answer: (4)