Register

Biology 30 – Nervous And Endocrine System Practice Test

Access More Questions
Which hormone produced by the thyroid increases metabolism and growth and contains 3 iodine atoms?
Correct Answer:
Triiodothyronine (T3)
Explanation:
Thyroid hormones regulate how fast cells use energy and how they grow. The hormone with three iodine atoms is tri-iodo-thyronine (T3), and it is the more active form. T3 enters cells and binds to receptors in the nucleus, turning on genes that raise cellular respiration, heat production, and overall metabolic rate. This heightened metabolism supports growth by boosting protein synthesis and interaction with growth signals. The thyroid also makes thyroxine (T4), which has four iodines and mainly serves as a storage/precursor that is converted into T3 in tissues. Calcitonin and parathyroid hormone regulate calcium levels rather than metabolism, so they don’t fit the description.

Access more questions from this quiz

Continue to Biology 30 – Nervous and Endocrine System Practice Test for more practice questions and the full quiz experience.

Access More Questions