Question

Birth rate minus death rate is known as
A. Reproductive rate
B. Population index
C. Population density
D. Population frequency

Answer 1

Hint:- The birth rate is the ratio between the number of live-born births in the year and the average population of the year. The death rate can be defined as the ratio of deaths in the year divided by the average population of the year.

Complete answer:
The increase in population occurs when there is an increase in the birth rate. That can be attained when there is increased birth compared to death. There will be a decrease in population when there is an increase in the death rate in the population. That will be caused when the death rate is more than the birth rate. Other factors that can cause a change in the population size is immigration, emigration, migration.
● Reproductive rate- it measures the condition under which generations are replaced. They can be calculated by taking mortality into account or without taking mortality into account.
● Population index- It is used to summarise population dynamics. This can be calculated by subtracting the death rate from the birth rate.
● Population density- It is the number of individuals per unit area.
● Population frequency- It is calculated by counting how many times the allele has appeared in a population and dividing it by the total number of copies of the gene.
Birth rate minus death rate is known as population index. So, the correct answer is option B.

Note:- Animals usually migrate from the population during the adverse condition and return to the population when the suitable condition returns. Animals generally migrate for food and reproduction.