What is the reason for the growth of the pollen tube towards the ovule?

$(a)$ If the cerebellum is not functioning properly,what are the activities of our body affected?
$(b)$ How do muscle cells move?

$(a)$ How are the movement of leaves of touch-me-not and the growth of a stem towards light different?
$(b)$ What is chemotropism? Give one example.
$(c)$ What is tropism?

Write true or false for the statement: Growth of pollen tubes towards ovules is due to chemotropism.

State whether the following statement is true or false: Abscisic acid inhibits growth.

Give a reason to explain why:
$(i)$ Adrenaline helps in dealing with emergency situations?
$(ii)$ Secretions of growth hormone should be specific in the human body?
$(iii)$ Some patients of diabetes are treated by giving injections of insulin?