Which of the following hormones requires iodine for its synthesis?

The growth of pollen tubes towards ovules is due to:

The junction between two neurons is called:

What are hormones?

Define 'nerve impulse'. Which structure in a neuron helps to conduct a nerve impulse:
$(i)$ towards the cell body?
$(ii)$ away from the cell body?

$(a)$ 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.