Question

In N = population density at time t, then population density at time +1 can be written as
${N_t} + 1 = {N_1} + [(A + B) - (C + D)]$
Select the correct option for A, B, C and D in the above equation.
(A) A can be mortality and B can be natality
(B) B can be immigration and C can be natality
(C) C can be mortality and D can be immigration
(D) A can be natality and D can be emigration

Answer 1

Hint:The measurement of population per unit area or unit volume at a particular time is called population density. In physics, the ratio of mass to volume is called density.

Complete answer:
If N = population density time t, then population density as time ${t_1}$is written as
${N_t} + 1 = {N_1} + [(A + B) - (C + D)]$
In this equation. A can be natality and D can be emigration.
The population density is a geographical term. It is dissociated with the amount or quantity of population found over a particular geographical area in a particular time.
The factors that play an important role in the determination of population are natality, mortality and the rate of migration.
(1) Natality: The birth rate is called natality. The rate at which birth takes place over a particular area is called natality. If there is an increase in the rate of birth, the population of a place increases.
(2) Mortality: The rate of death in a particular origin is called mortality. If the mortality rate increases, the population of places decreases.
Thus for obtaining a stable population for an area, the difference between birth rate and death rate is calculated.
(3) Migration: The movement of an organic from a place to another for basic requirements is called migration. There can be several reasons for migration such as educational factors, livelihood, job Opportunities etc.
(a) Emigration: The migration in which the act of lining a place takes place is called Immigration.
Population decreases as a result of emigration.
(b) Immigration: When there is an entry to a particular place or geographical area, it is called immigration. Immigration increases the population of an area.
Hence the correct answer is option ‘D’.

Note: In the equation ${N_t} + 1 = {N_1} + [(A + B) - (C + D)]$
A is the natality, B is immigration and C is mortality and D is emigration.
To obtain the population of a particular area, mortality and emigration is subtracted from total of natality and immigration.