Certain chemical substances having a profound effect on growth are called

Classical experiments on growth were performed by

Plant growth regulators $(PGRs)$ are

Which of the following substances act as a key growth regulator?

In animals,there are special glands secreting hormones,whereas there are no glands in plants. Where are plant hormones formed? How are the hormones translocated to the site of activity?

Mention the characteristics and types of plant growth regulators.