Water is made up of the elements hydrogen and oxygen. The smallest particles of matter are called atoms. Remember the carrot from the other chapter. If you continue to chop a carrot into smaller and smaller pieces, eventually you would reach a point where you could not cut up the carrot anymore, but still have carrot.
occult blood test. a test for the presence of microscopic amounts of blood in the feces secondary to bleeding in the digestive tract. The minimal amounts of occult blood normally passed into the GI tract are not usually significant enough to cause a positive result for occult blood testing.
occult blood. occult blood in Medicine. occult blood n. Blood that is present in amounts too small to be seen and can be detected only by chemical analysis or microscopic examination. Discover our greatest slideshows.