Which of the following inhibits the enzyme acetylcholinesterase?

Parkinson's disease,characterized by tremors and rigidity of limbs,is caused by the degeneration of brain cells involved in movement control and the use of which neurotransmitter?

The brief delay in the transmission of an impulse through a synapse is called .........

The neurotransmitter which communicates between two neurons or between a neuron and a muscle is

Arrange the following events in proper sequence during impulse transmission across a chemical synapse:
$(a)$ Fusion of synaptic vesicles with the cell membrane of the presynaptic neuron.
$(b)$ $Ca^{++}$ channels open and $Ca^{++}$ diffuses into the synaptic knob from the extracellular fluid.
$(c)$ Neurotransmitter binds with receptors of the postsynaptic cell.
$(d)$ Release of neurotransmitter by exocytosis.

The given diagram shows the axon terminal and synapse. Identify the correct pair of any two labels from $A$ to $D$.