AP BIOLOGY

Detailed explanation-1: -The rate of natural increase refers to the difference between the number of live births and the number of deaths occurring in a year, divided by the mid-year population of that year, multiplied by a factor (usually 1, 000). It is equal to the difference between the crude birth rate and the crude death rate.

Detailed explanation-2: -The net reproductive rate (r) is the percentage growth after accounting for births and deaths. In the example above, the population reproductive rate is 0.5%/yr. Net reproductive rate (r) is calculated as: r = (births-deaths)/population size or to get in percentage terms, just multiply by 100.

Detailed explanation-3: -Population Growth Calculation To calculate the Population Growth (PG) we find the difference (subtract) between the initial population and the population at Time 1, then divide by the initial population and multiply by 100.

Detailed explanation-4: -Natural decrease occurs when death rate is greater than birth rate. This means that more deaths occur in a population than babies are born so population numbers decline.