What happens at the synapse between two neurons?

Which of the following statements are true?
$(i)$ Sudden action in response to something in the environment is called reflex action.
$(ii)$ Sensory neurons carry signals from the spinal cord to muscles.
$(iii)$ Motor neurons carry signals from receptors to the spinal cord.
$(iv)$ The path through which signals are transmitted from a receptor to a muscle or a gland is called a reflex arc.

Match the terms of Column $(A)$ with those of Column $(B)$.

Column $(A)$	Column $(B)$
$(a)$ Olfactory receptors	$(i)$ Tongue
$(b)$ Thermoreceptors (temperature receptors)	$(ii)$ Eye
$(c)$ Gustatoreceptors	$(iii)$ Nose
$(d)$ Photoreceptors	$(iv)$ Skin

Name the plant hormones responsible for the following:
$(a)$ Elongation of cells
$(b)$ Growth of stem
$(c)$ Promotion of cell division
$(d)$ Falling of senescent leaves.

In a neuron,conversion of electrical signal to a chemical signal occurs at/in:

Which mechanism controls the timing and amount of hormone released?