AP BIOLOGY

Detailed explanation-1: -Mass extinction events may be caused by comet and asteroid impacts, widespread volcanism, climatic changes, rapid changes in geography and ocean currents, or combinations of these factors. Extinction, which refers to the dying out of a single species, is a feature of Earth’s flora and fauna.

Detailed explanation-2: -A mass extinction is a short period of geological time in which a high percentage of biodiversity, or distinct species-bacteria, fungi, plants, mammals, birds, reptiles, amphibians, fish, invertebrates-dies out.

Detailed explanation-3: -This is known as the background rate of extinction. A mass extinction event is when species vanish much faster than they are replaced. This is usually defined as about 75% of the world’s species being lost in a ‘short’ amount of geological time-less than 2.8 million years.

Detailed explanation-4: -Some 252 million years ago, life on Earth faced the “Great Dying”: the Permian-Triassic extinction. The cataclysm was the single worst event life on Earth has ever experienced. Over about 60, 000 years, 96 percent of all marine species and about three of every four species on land died out.

Detailed explanation-5: -Although the best-known cause of a mass extinction is the asteroid impact that killed off the non-avian dinosaurs, in fact, volcanic activity seems to have wreaked much more havoc on Earth’s biota. Volcanic activity is implicated in at least four mass extinctions, while an asteroid is a suspect in just one.