Which of the following would explain the extinction of upwards of 90% of species in existence over a short period of time?
(a) mass extinction events
(b) dispersal events
(c) speciation
(d) endemic population

A

Explanation:

These are rapid events that cause the rapid decrease in the biodiversity on earth at a time. An example of such as mass extinction event is the Permian-Triassic extinction that is believed to have occurred approximately 250 million years ago. This extinction event is believed to have been caused by an asteroid strike that wiped out the famous dinosaurs and other life on earth.

A. Mass Extinction Events

Explanation - The process in which most of the species of the organism dies then it is called as extinction. Extinction can be due to various reasons like limiting factor, unfavourable environmental conditions, human activities etc.

In recent years, the above mentioned factors are responsible for extinction. Due to disposal of plastic bags in the water bodies and soil chokes the organisms leading to death. If extinction occurs in large rate then the ecological balance will get disturbed.

option a and d is the correct answer

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the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus