MODEL PAPER 9 — BIOLOGY STD 12 Science — Question

Extinction of species: The extinction of species is a natural process. Many species have disappeared and new ones have evolved to take over their place. There are three types of extinction processes:
i. Natural extinction: When there is a change in environmental conditions, certain species disappear and others, (which are more adapted to changed conditions) take their place. This loss of species that occurred in the geological past at a very slow rate is known as natural (background extinction).
ii. Mass extinction: There have been several periods in the earth's geological history when a large number of species became extinct due to catastrophes.
iii. Anthropogenic extinction: Recently more number of species is disappearing from the face of the earth due to human activities. Man-made mass extinction represents a very severe depletion of biodiversity.