EVERYDAY SCIENCE

Detailed explanation-1: -The change in the population size of a country during a specific period of time is called Population growth. The growth of population in a region depends upon fertility, mortality and migration. Fertility or the birth rate is measured in terms of total number of live births per thousand population per year.

Detailed explanation-2: -Population growth rate (r) is how fast a population changes in size over time. A positive growth rate means a population is increasing. A negative growth rate means it is decreasing. The two main factors affecting population growth are the birth rate (b) and death rate (d).

Detailed explanation-3: -Overall, population grows or shrinks through two very basic components: natural change (births minus deaths) and migration (domestic plus international).

Detailed explanation-4: -As a result of declining fertility rates, global population growth is slowing. Over the four decades from 1970 to 2010, the number of people on Earth grew nearly 90%. From 2010 to 2050, the world’s population is expected to rise 35%, from roughly 7 billion to more than 9 billion.

Detailed explanation-5: -There are three main processes of change of population. They are birth rates, death rates, and migration. The natural increase of population is the difference between birth rates and death rates.