Which of the following is NOT a part of the excretory system?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Thyroid gland
The excretory system removes nitrogenous wastes from the body as urine. In humans it is made up of the two kidneys, two ureters, the urinary bladder and the urethra.
Option (1) Kidney — filters the blood and forms urine; the main organ of excretion.
Option (2) Urinary bladder — a muscular bag that stores urine brought down by the ureters.
Option (3) Thyroid gland — an endocrine gland in the neck that makes the hormone thyroxine, which controls the body’s rate of metabolism, so the thyroid gland is not a part of the excretory system.
Option (4) Urethra — the tube that carries urine out of the body from the bladder.