Question

Which of the following hormones require iodine for its synthesis?
A. Adrenaline
B. Thyroxine
C. Auxin
D. Insulin

Answer 1

Iodine is a mineral found in some foods like fish and other seafood, dairy products, fruits and vegetables and iodized salt. Iodine mineral helps thyroid gland in making thyroid hormones in the body which are required for normal growth and development of the body. Iodine is absorbed in both stomach and small intestine and it is concentrated from the bloodstream into the follicular cell of the thyroid. Thyroid hormones are firstly secreted as the prohormone thyroxine and should be activated in the tissues in the form of triiodothyronine.

Complete Solution:
The thyroid hormones are secreted with the help of iodine present in our body which help in optimum growth and development of the body. These thyroid hormones are triiodothyronine known as ${T_3}$ and thyroxine which is known as ${T_4}$. These both hormones are tyrosine based hormones which are produced by the thyroid gland which is responsible for proper functioning of the metabolism. The deficiency of these two thyroid hormones enlarges the thyroid tissue and causes disease called simple goiter. The major form of thyroid hormone which is present in blood is thyroxine and the ratio of these hormones ${T_3}$ to ${T_4}$ in the human body is 1:14.

Hence, the correct option is B. Thyroxine.

Note: The regulation of thyroid hormone production and metabolism helps in optimum thyroid hormone action in the tissues if there is fluctuation in the supply of iodine in the body. In some conditions like during pregnancy, this mechanism does not apply as it is not sufficient to compensate and leads to normal fetal development.