Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which system is responsible for delivering oxygen to the bloodstream?

1. Digestive system

2. Circulatory system

3. Respiratory system

4. Nervous system

The correct answer is: Respiratory system

The respiratory system is responsible for delivering oxygen to the bloodstream through the process of breathing. When air is inhaled, it travels through the respiratory passages into the lungs, where oxygen is exchanged for carbon dioxide in the alveoli, tiny air sacs located in the lungs. This exchange occurs due to the differences in concentration of oxygen and carbon dioxide in the air and blood. Once the oxygen enters the bloodstream, it binds to hemoglobin in red blood cells and is transported to the body’s tissues, enabling cellular respiration and energy production. The other systems mentioned have their distinct roles; the digestive system primarily processes food and absorbs nutrients, the circulatory system is responsible for transporting substances like oxygen and nutrients throughout the body after they have entered the bloodstream, and the nervous system controls and coordinates bodily functions and responses but does not have a direct role in oxygen delivery.