Answer:
Thyroid
Step-by-step explanation:
The thyroid gland releases triiodothyronine and thyroxine hormones that regulate the metabolic rate of the body. These thyroid hormones do not have specific target organs. These hormones stimulate the body cells to increase the rate of cellular respiration and thereby to increase the rate of breakdown of glucose to release energy.
The energy released is used for various functions and growth and development by cells. Hence, the thyroid gland regulates the metabolic rate by increasing the rate of cellular respiration.