12th Standard Geography — Population Geography Online Test
Unit 1 of Class 12 Geography explains how the world's population is distributed, how density is measured, how and where it grows, and how it is composed by sex, literacy and age. It also covers migration, brain drain, the impacts of overpopulation and the measures to control it.
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About Population Geography
Medium ~60 min study
Population Geography is the first unit of the Tamil Nadu State Board Class 12 (Plus Two) Geography book. It opens with a striking fact: about 3,60,000 people are born every day, four births every second, and population explosion is one of the greatest challenges we face today.
The unit defines demography, explains the five factors that shape population distribution, and divides the world into areas of high, moderate and low density. It then traces world population growth, doubling time, composition, migration and overpopulation, with case studies on literacy in Kerala, Bihar and Tripura.
This page gathers the one mark questions of the book exercise with answers checked against the lesson, plus additional questions on density, growth, pyramids, migration and overpopulation, each with a short explanation.
What you'll learn
- Define demography and list the factors that influence population distribution.
- Calculate arithmetic density and explain physiological or nutritional density.
- Name the areas of high, moderate and low population density.
- Work out doubling time with the Rule of 70.
- Read expansive, constrictive and stationary age-sex pyramids.
- Distinguish the types of migration and the push and pull factors.
- Explain the impacts of overpopulation and the measures to control it.
Before you start
- Basic idea of percentages and ratios.
- A world map showing the continents, major river valleys and deserts.
- The meaning of census and birth and death rates from earlier classes.
Topics covered in this chapter
Population Geography explained
What this unit covers
Distribution and density
Relief, accessibility, water supply, soil and economic and political factors shape where people live. Density is total population divided by area; physiological or nutritional density uses cropped area instead. High density areas have more than 100 persons per sq.km, moderate areas 10 to 80, and low density areas fewer than 10.
Growth of world population
World population was 550 million around 1750 and 7.6 billion now, and is projected at 9.7 billion in 2050 and 11.2 billion in 2100. The Rule of 70 gives doubling time. Countries are grouped into areas of low, moderate and high growth rate.
Composition
Sex ratio, literacy rate and age-sex pyramids describe a population. Pyramids are expansive (Bangladesh), constrictive (USA) or stationary (Austria).
Migration
Net, international, internal, local, voluntary and involuntary migration, brain drain and the push and pull factors behind it.
Overpopulation
Its impacts on resources, habitats, climate, biodiversity, fresh water, life expectancy, jobs and farming, and six measures to control it.
Common mistakes to avoid
- Confusing arithmetic density (per unit of land area) with nutritional density (per unit of cropped area).
- Placing the central USA among high density areas; it is a moderate density area, while the north-eastern USA is high density.
- Thinking the receiving country loses talent in brain drain; it is the country of origin that loses it.
- Calling Qatar the country with the most females; Qatar has the highest male to female ratio, Latvia the highest sex ratio in favour of females.
- Mixing up the pyramid types: Bangladesh is expansive, the USA constrictive and Austria stationary.
Test yourself on these with the practice test, then check the worked reasoning in the solved MCQs.
Frequently asked questions
What is demography?
Demography is the statistical study of human population. It includes the study of size, structure and distribution of population as well as changes in time and location in response to birth, migration, aging and death.
What is physiological or nutritional density?
It is the ratio between total population and total cropped area, a more refined way of measuring the man-land ratio than simple arithmetic density. The world's nutritional density is 325 per sq.km and India's is 753 per sq.km, while Singapore has the highest in the world.
How is the doubling time of a population found?
Doubling time is the time a population takes to double in size at a constant growth rate. By the Rule of 70, divide 70 by the growth rate: a population growing at 1% doubles in 70 years, and one growing at 2.08% doubles in about 33.6 years.
What are the three types of age-sex pyramid?
Expansive pyramids have a large share of young people, high fertility and lower life expectancy, as in Bangladesh. Constrictive pyramids narrow at the base because birth rates are declining, as in the USA. Stationary pyramids show nearly equal shares in each age group, as in Austria.
What is brain drain?
Brain drain is an educationally specific, selective migration. The receiving country gains highly qualified labour without paying for its education and health. The country of origin loses potential leaders and talent, as when 15 to 40% of a graduating class in Canada moves to the US.
What are push and pull factors of migration?
A push factor is forceful and relates to the country a person leaves, such as unemployment, famine, persecution or natural disasters. A pull factor relates to the country a person moves to and attracts them, such as jobs, better living conditions, education, security and family links.
How can overpopulation be controlled?
The lesson lists six measures: creating awareness campaigns, promoting adoption, aiming for single-child families, treating population growth as a national security issue, respecting changing social norms, and giving tax benefits or concessions to couples with one or two children.
Last updated 19 October 2026