The passage describes the roles of different components of human blood in transport.
Complete the passage by writing a suitable word or words in each blank space.
The blood is a transport medium that carries various substances throughout the body.
Red blood cells are specialized cells that transport (1) \text{\____________________} from the lungs to respiring tissues. These cells are packed with an iron-containing protein called (2) \text{\____________________} which binds to this gas. To maximize the space available for this protein, mature red blood cells do not have a (3) \text{\____________________} .
The liquid part of the blood is called (4) \text{\____________________} . This liquid transports many dissolved substances around the body, including soluble food molecules such as (5) \text{\____________________} absorbed from the small intestine, and waste products like (6) \text{\____________________} which is transported to the lungs to be exhaled.
