- 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.
highly addictive substance found in tobacco that accelerates the heart rate, and contracts and...
water that is found on the surface of the earth, e.g. in rivers, streams, and lakes etc.
a species that has been introduced into an area in which it did not previously or naturally...