$(a)$ Define reflex arc. Draw a flow chart showing the sequence of events which occur during sneezing.
$(b)$ List four plant hormones. Write one function of each.

(N/A) reflex arc is the neural pathway that controls a reflex action. It is the path taken by nerve impulses in a reflex action,from the receptor to the effector.
Flow chart for sneezing:
Unwanted particles in the nostril $\to$ Receptors $\to$ Sensory neuron $\to$ Spinal cord $\to$ Motor neuron $\to$ Effectors (muscles of the respiratory system) $\to$ Sneezing.
$(b)$ Four plant hormones and their functions:
$1$. Auxins: Promote cell elongation and growth.
$2$. Gibberellins: Promote stem elongation and seed germination.
$3$. Cytokinins: Promote cell division.
$4$. Abscisic acid: Inhibits growth and promotes seed dormancy or leaf wilting.