Question

lo 4.3. what is the respiratory system responsible for?
maintenance of acid - base balance
regulation of body temperature
transportation of nutrients
exchange of gases
production of hormones

Explanation:

The respiratory system's main function is gas exchange. It takes in oxygen ($O_2$) from the environment and releases carbon dioxide ($CO_2$) produced by cellular respiration. While the respiratory system can play a minor role in acid - base balance (by regulating $CO_2$ levels which affects carbonic acid formation), its primary and most characteristic role is gas exchange.

• Maintenance of acid - base balance: While related (via $CO_2$ levels), not the primary function.
• Regulation of body temperature: Mainly the skin (e.g., sweating) and circulatory system (e.g., vasodilation/vasoconstriction) are involved.
• Transportation of nutrients: That is the role of the circulatory system.
• Production of hormones: Endocrine glands are responsible for hormone production.

Answer:

Exchange of gases