Multiple choice Where does the exchange of gases take place during breathing? Nostrils Trachea Alveoli Bronchioles Reveal answer Fill a bubble to check yourself C Correct answer Explanation The exchange of gases takes place in the alveoli. The walls of the alveoli are surrounded by a network of blood capillaries. Thin walls of alveoli and capillaries allow for O2 to enter the capillaries and CO2 to enter the alveoli for exhalation.