A Level Biology Practice Exam 2026 – All-in-One Study Guide to Excel in Your A Levels!

The main function of the respiratory system is indeed gas exchange. This process involves taking in oxygen from the environment and expelling carbon dioxide, which is a waste product of cellular respiration. Oxygen is vital for the production of energy in the form of ATP, which cells use to perform various functions, while the removal of carbon dioxide helps maintain acid-base balance in the body.

The other options, while related to different physiological systems, do not accurately reflect the primary role of the respiratory system. For example, digestion of food is handled by the digestive system, the transport of nutrients is primarily the responsibility of the circulatory system, and the regulation of body temperature is mostly managed by the integumentary system and other mechanisms. The focus of the respiratory system remains central to facilitating the exchange of gases necessary for cellular metabolism and overall homeostasis.