- Life Sciences
a tough substance made from a modified polysaccharide that contains nitrogen. It is the main component of the exoskeletons of arthropods, the cell walls of fungi, the radula's of molluscs and the beaks of cephalopods.
the blood vessel that carries blood from the digestive tract to the liver.
(also called the pith) the central part of the stem that consists of large, thin-walled...
chlorofluorocarbons (CFCs) are organic compounds that contain carbon, chlorine and fluorine.