Biology STAAR Practice Test 2025 - Free State of Texas Assessments of Academic Readiness Practice Questions and Study Guide

The testes produce testosterone, which is a steroid hormone that plays a crucial role in male sexual development and function. Testosterone is responsible for the development of male secondary sexual characteristics during puberty, such as increased muscle mass, facial hair growth, and deepening of the voice. It also regulates libido, sperm production, and overall male reproductive health.

The other hormones listed are produced by different glands and have distinct functions. Insulin, for example, is produced by the pancreas and is essential for regulating blood glucose levels. Adrenaline is produced by the adrenal glands and is involved in the body's fight or flight response. Thyroxin, also known as T4, is produced by the thyroid gland and helps regulate metabolism. Each of these hormones serves unique roles in the body's physiology, distinguishing them from testosterone which is specifically linked to male reproductive health.