Caffeine: alkaloid present in coffee What is alkaloid Alkaloid is any component of the group of plant-derived organic nitrogen compounds. Alkaloids have several pharmacological properties, ie they can be used in the manufacture of medicines. Most alkaloids are used in medicine as analgesics and anesthetics.
Extinction (the complete disappearance of a species from Earth) is an important part of the evolution of life on Earth. The current diversity of species is a product of the processes of extinction and speciation throughout the previous 3.8 billion year history of life. Raup (1991) assumed that there might be 40 million species alive today, but between 5 and 50 billion species have lived at some time during the history of the Earth.