Groups are determined by PRECIPITIN test, serologic test to measure a specific reaction between antigen (C carbohydrate, located in the cell wall) and antibody which results in a visible precipitate. Group A Streptococci (Streptococcus pyogenes) is among the most important human pathogens.
Answers.comÂ® is making the world better one answer at a time. Striking an object is the leading cause of pwc accidents on boats.
Causes of Down Syndrome. From what is known about the causes of Down syndrome, environmental factors and parents' behavioral activity do not seem to play a role. Most cases (approximately 92 percent) are caused by trisomy 21, which means each cell in the body has three copies of chromosome 21 instead of the usual two copies.