Which of the following statements about hormones is incorrect?

The correct answer is Option (3) → Hormone insulin is released when there is rapid fall in blood glucose level.

Insulin keeps the blood glucose level within a narrow limit by lowering it, so it is released in response to a rapid rise in blood glucose. When the glucose level falls, it is glucagon that acts, by raising it.

• Option (1) Hormones act as messengers between glands and receptors. — A correct statement about hormones. They are released by endocrine glands into the blood and carry the message to the target cells.

• Option (2) Male sex hormones are used by athletes and sportsperson to increase muscle strength. — A correct statement about hormones. Testosterone-type (anabolic) steroids build muscle, which is why their use is banned in sport.

• Option (3) Hormone insulin is released when there is rapid fall in blood glucose level. — An incorrect statement about hormones. Insulin is released on a rapid rise in blood glucose; a fall calls for glucagon.

• Option (4) Abnormally low levels of thyroxine is characterized by obesity and lethargy. — A correct statement about hormones. Low thyroxine causes hypothyroidism, marked by lethargy and obesity.

NCERT (2026-27 edition):
Hormones – “… Hormones have several functions in the body. They help to maintain the balance of biological activities in the body. The role of insulin in keeping the blood glucose level within the narrow limit is an example of this function. Insulin is released in response to the rapid rise in blood glucose level. On the other hand hormone glucagon tends to increase the glucose level in the blood. The two hormones together regulate the glucose level in the blood. … Thyroxine produced in the thyroid gland is an iodinated derivative of amino acid tyrosine. Abnormally low level of thyroxine leads to hypothyroidism which is characterised by lethargyness and obesity.”