The largest endocrine gland is:

An organ $X$ has a large blood supply. It produces a hormone,the lack of which causes a disease known as cretinism. The organ is

The energy-releasing process in body cells is initiated by which of the following glands?

Calcitonin lowers the calcium level in the blood. This is secreted by

$I.$ Hypothyroidism causes irregularity of the menstrual cycle.
$II.$ Hyperthyroidism adversely affects body physiology.
$III.$ Hypothyroidism causes cretinism.
$IV.$ Hypothyroidism causes goitre.
Which of the above statements are correct?

$A$ health disorder that results from the deficiency of thyroxine in adults and is characterised by $(i)$ a low metabolic rate,$(ii)$ an increase in body weight,and $(iii)$ a tendency to retain water in tissues is: