Understand the definition of steroid hormones: Steroid hormones are a class of hormones that are derived from cholesterol and include sex hormones and adrenal cortex hormones.
Identify the common steroid hormones: Testosterone and estrogen are sex hormones, while cortisol is an adrenal cortex hormone. All are derived from cholesterol.
Recognize the structure of steroid hormones: Steroid hormones typically have a four-ring structure known as the cyclopentanoperhydrophenanthrene ring system.
Consider the function and origin of insulin: Insulin is a peptide hormone produced by the pancreas, not derived from cholesterol, and does not have the characteristic steroid structure.
Conclude which hormone does not fit the steroid category: Based on the structural and functional differences, insulin is not a steroid hormone.