List five main groups of natural plant growth regulators. Write a note on discovery, physiological functions and agricultural/ horticultural applications of any one'of them.

Write the names of hormones and the glands secreting them for the regulation of following functions. Secretion of growth hormone.

Write the names of hormones and the glands secreting them for the regulation of following functions. Growth of thyroid and secretion of thyroxine.

Write the names of hormones and the glands secreting them for the regulation of following functions. Helps in relaxing pubic ligaments to facilitate easy birth of young ones.

Answer the following questions: Give any four functional group containing oxygen as the heteroatom in it. Write name and structural formula and one example each.