Which tropic movement is responsible for the growth of pollen tubes towards ovules?

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?

What is meant by hydrotropism? Give an example.

Dramatic changes of body features associated with puberty are mainly because of the secretion of:

$(a)$ Name one organ each where growth hormone is synthesized in man and plant.
$(b)$ List the sequence of events that occur when a plant is exposed to unidirectional light,leading to bending of a growing shoot. Also,name the hormone and the type of movement.

What is the gap between two neurons called?