The hormones secreted from which gland regulate the function of the pituitary gland?

Give reasons :
$(a)$ Pituitary is often termed as master endocrine gland.
$(b)$ Pancreas helps in digestion and also regulates blood sugar level.
$(c)$ Adrenals are known as glands of emergency.

$(a)$ Define hormone. Write four characteristics of hormones in humans.
$(b)$ Name the disorder caused by the following situations:
$(i)$ Under secretion of growth hormone
$(ii)$ Over secretion of growth hormone
$(iii)$ Under secretion of insulin
$(iv)$ Deficiency of iodine

How does the feedback mechanism regulate hormone secretion?

Which gland produces the hormone thyroxine?

$(a)$ Name the hormone which is released into the blood when its sugar level rises. Name the organ which produces this hormone and its effect on blood sugar level. Also, mention the digestive enzymes secreted by this organ with one function of each. $(b)$ Explain the need for chemical communication in multicellular organisms.