Biology Regents Practice Exam

The circulatory system plays a crucial role in maintaining homeostasis within the body by transporting essential substances to and from cells. Its primary function is to deliver nutrients—such as glucose and vitamins—oxygen, and hormones to various tissues and organs, while also facilitating the removal of waste products such as carbon dioxide and metabolic byproducts. This transport system ensures that all cells receive the materials they need to function effectively, supporting overall health and vitality.

In addition to its primary functions related to transport, the circulatory system also plays a pivotal role in regulating body temperature and supporting immune responses, but these functions are secondary to its main task of nutrient and gas transport. Thus, the comprehensive role of the circulatory system can best be summarized by option B, which captures its essential responsibilities within the larger context of body function.