(N/A) population has certain attributes that an individual organism does not.
An individual may have births and deaths,but a population has birth rates and death rates.
In a population,these rates refer to per capita births and deaths,respectively.
The rates are expressed as the change in numbers (increase or decrease) with respect to the members of the population.
Another attribute characteristic of a population is the sex ratio.
An individual is either a male or a female,but a population has a sex ratio (e.g.,$60\%$ of the population are females and $40\%$ are males).
$A$ population at any given time is composed of individuals of different ages.
If the age distribution (percentage of individuals of a given age or age group) is plotted for the population,the resulting structure is called an age pyramid.
For the human population,age pyramids generally show the age distribution of males and females in a combined diagram.
The shape of the pyramids reflects the growth status of the population: $(a)$ growing,$(b)$ stable,or $(c)$ declining.