What test did forensic scientists use to link blood to an individual until the 1990's?

The standard test used to determine whether blood is of human or animal origin is the precipitin test. This test is based on the fact that when animals (usually rabbits) are injected with human blood, antibodies are formed that react with the invading human blood to neutralize its presence.

protein synthesis is an example of feedback mechanism which in homeostasis

the correct answer is - ability to find a mate