The ability to taste Thiourea and Phenylthiocarbamide is genetic.These PTC (Thiourea-Phenylthiocarbamide) Taste Papers are either bitter or tasteless depending on the genetics & heredity of taster. Give students the opportunity to discover whether they are a taster or non-taster in comparison with the rest of the class.Each individual should take the taste test only once.Paper strip dimensions 9mm x 50mm (25 strips on each pad).Pack of 100 stripsPlease note: the date on the label is the production date not an expiry date.