7
Blood: Test Your Understanding (continued)
Teacher's Guide
+
ward
'
s
science
Critical Thinking: What is the advantage of having prothrombin instead of thrombin in the blood?
Thrombin is the principal enzyme responsible for blood coagulation. The presence of the active
enzyme within the bloodstream would lead to the coagulation of blood within the circulatory system.
By requiring cleavage from a precursor (prothrombin), thrombin activity can be limited to the sites
and circumstances in which coagulation is required (for example, a wound).
Critical Thinking: What is the importance of mechanisms that keep the pH of blood at 7.4?
Consistent blood pH is important to the function of enzymes, which require a narrow pH range and
perform important functions in the blood (for example, clotting and anti-proteolytic activity).
7
