Final answer:
Organisms synthesize carrier molecules to deliver high oxygen concentration. Hemoglobin in red blood cells binds oxygen and facilitates its transport. Synthetic oxygen carriers called 'blood substitutes' can also be used to increase oxygen concentration in emergencies.
Step-by-step explanation:
In order to deliver a high concentration of oxygen (60% to 95%), organisms synthesize carrier molecules that bind oxygen reversibly. For example, human red blood cells contain a protein called hemoglobin that specifically binds oxygen and transports it from the lungs to the tissues. Hemoglobin allows for a much higher concentration of dissolved oxygen in the blood, compared to what would be possible without it. Synthetic oxygen carriers known as 'blood substitutes' have also been developed to increase oxygen concentration in emergencies.