Chapter 5.2, Problem 4MI

Summary Introduction

To fill:

The correct terms in the given blanks.

Introduction:

Species of birds like passenger pigeons, blue pike, and sparrows are now extinct. Species are at risk of extinction when their habitats are destroyed. Scientists have developed several programs to save the species from getting extinct. Biodiversity brings stability to an ecosystem. A change in species can destabilize it.

Answer to Problem 4MI

The given blanks can be filled as follows:

S. no.	Correct term
1	Background extinction
2	Ecosystem
3	Biotic crisis
4	Mass extinction

Explanation of Solution

Extinction is disappearance of a particular species when the last of its members dies. Extinction is a natural process and our Earth has experienced several mass extinctions during its history. There is also some degree of natural extinction called background extinction that goes on. It is very slow and gradual. Scientists estimate that background extinction accounts for the loss of one species per year per million species. However, the current rate of extinction exceeds that by many times, this increased rate of extinction indicates biotic crisis. This dramatic increase in mass extinction could be due to the loss of habitat, expansion of human population, and land exploitation.