An association football (soccer) match is presided over by a referee, whom the Laws of the Game give full authority to enforce the Laws of the Game in connection with the match to which he has been appointed (Law 5). The referee is oftentimes assisted by two assistant referees, and sometimes by a fourth official.
Barfoed's test. Barfoed's test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of copper(II) acetate to copper(I) oxide (Cu2O), which forms a brick-red precipitate.
The guaiac-based fecal occult blood test (gFOBT) detects blood in the stool through a chemical reaction. This test cannot tell if the blood is from the colon or from other parts of the digestive tract (such as the stomach).If this test is positive, a colonoscopy will be needed to find the reason for the bleeding.he guaiac-based fecal occult blood test (gFOBT) detects blood in the stool through a chemical reaction. This test cannot tell if the blood is from the colon or from other parts of the digestive tract (such as the stomach).