Which part of the hemoglobin molecule directly interacts with oxygen?

The blood type that contains both antigens A and B is ________.

What is the main function of the lymphatic system? 

The blood type that contains both antigens A and B is ________.

Quickly explain how the innate and adaptive immune systems differ in their responses to foreign substances.

Which of these descriptions best matches the term B cells?

Which ion is essential for blood clotting to occur?

In adults, the ______________ is the only site of red blood cell production, and the primary site of white blood cell formation. 

The green structure indicated here is called the __________.

The green structure indicated here is called the __________.