Advanced Placement (AP) Biology Practice Exam

The growth hormone is primarily known for its role in promoting the growth of bones and tissues. It stimulates the growth plates in the bones to increase in size, which contributes to overall height during development. Additionally, growth hormone encourages the proliferation of chondrocytes, which are cells that contribute to cartilage formation, further aiding bone growth.

While metabolism can be influenced by growth hormone, the direct stimulation of bone growth is a more specific and well-defined function. Growth hormone also promotes protein synthesis and affects lipid metabolism but its main action is in the growth and development of skeletal tissues, especially during childhood and adolescence. The other choices, such as the production of red blood cells and energy storage, are not the primary actions of growth hormone. While it may have some ancillary effects on metabolism and energy regulation, its fundamental role centers on stimulating growth in bones and other tissues.