Question

Which among the following are attributes of a population?
i. Birth
ii. Death
iii. Birth rate
iv. Death rate
v. Sex or gender
vi. Sex ratio

• A. i, ii, iii and iv
• B. v and vi
• C. i, ii and v
• D. iii, iv and vi

Answer 1

The correct option is D iii, iv and vi

A population is a group of individuals of the same species living in a particular geographical area and capable of potentially interbreeding with each other to produce fertile offspring.

Population has certain attributes (features) which are not exhibited by individual organisms.

Birth rate, death rate and sex ratio are certain attributes of the population.

Birth rate can be defined as the ratio between the number of individuals born in an existing population and the initial population size, in a given time period.

For example, in a pond, 20 fishes were present last year and 8 new fishes are added through reproduction this year, taking the current population to 28.

Then the birth rate can be calculated by using the formula:

$\frac{Numberofindividualsadded\left(births\right)}{Initialpopulationsize}$
= 8/20 = 0.4 offspring per fish per year.

Death rate can be defined as the ratio between the number of individuals died and the initial population size, in a given time period.

For example, if in a laboratory population of 40 fruit flies, 4 flies died within a week, then the death rate can be calculated using the formula

$\frac{Numberofindividualsdied}{Initialpopulationsize}$
= 4/40
= 0.1 individuals per fruit fly per week.

The birth rate and death rates are calculated per capita i.e., per head or each individual added or lost in a given population.

An individual can either be male or female, it defines the gender of the individual but ‘sex ratio’ is an attribute of a population. It is basically the ratio of males to females in a population.

Therefore, birth rate, death rate and sex ratio are attributes of a population.