Question

Which of the following hormones contains iodine?
A. Insulin
B. Thyroxine
C. Adrenaline
D. Testosterone

Answer 1

As we know hormones are chemical substances that affect the activity of another part of the body that is on the target site. It is secreted by endocrine glands directly into the bloodstream. The hormone that contains iodine is secreted by the thyroid gland.

Complete step by step answer:
Now we also know that the glands that secrete the hormone comprise the endocrine signalling system. Let us see what endocrine signalling system is in brief:
An endocrine system is a chemical messenger system which comprises feedback loops of the hormones released by internal glands of an organism directly into the circulatory system which regulates distant target organs.

Now we will analyse all options step by step:

Insulin: It is a peptide hormone. It is produced in the beta cells of the pancreas. A single protein that is the monomer of human insulin is composed of 51 amino acids which have a molecular mass of 5808 Da. It maintains the metabolism of macronutrients by promoting glucose absorption from blood into skeletal muscles, liver and fat.
Now we will analyse peptide hormone in brief: As we know peptide hormone also known as protein hormones whose molecules are peptides or proteins respectively.
Thyroxine: As we know thyroid hormones produced two hormones that are released by the thyroid gland namely triiodothyronine (T3) and thyroxine(T4). These are tyrosine-based hormones that are responsible for the regulation of metabolism. These two hormones are partially composed of iodine. When iodine is deficient it leads to decreased production of t3 and t4 which enlarges the thyroid gland and will cause the disease known as simple goitre.
Adrenaline: As we know adrenaline also known as epinephrine produced by both the adrenal glands and a small number of neurons present in the medulla oblongata where it acts as a neurotransmitter. It plays an important role in the fight-or-flight response by increasing blood flow to the muscles and blood sugar level.
Testosterone: As the name suggests, testosterone is the primary male sex hormone that plays a key role in the development of male reproductive tissues such as testes and prostate. In addition, testosterone is involved in the prevention of osteoporosis.

Hence, from the above, it is concluded that the correct option is (B).

Note: Remember, do not confuse here endocrine glands with exocrine glands because as we have seen endocrine glands release chemical substances directly into the bloodstream or tissues of the body whereas exocrine glands release chemical substances through ducts to outside of the body.