Population Dynamics ICSE Class 8: Distribution, Growth and Composition

What Population Dynamics is about

Weightage: CISCE publishes no question paper, marking scheme or chapter weightage for Class VIII Geography: your school sets and marks the exam. Population Dynamics sits in the Population Dynamics theme of the CISCE Curriculum for Upper Primary Classes (VI-VIII).Source: CISCE Curriculum for Upper Primary Classes (VI-VIII), RDCD 2016

Key concepts

Distribution of population in the world

Population distribution is the way people are spread over the Earth's surface. It is very uneven.
Densely populated regions: East Asia (eastern China, Japan, Korea), South Asia (the Ganga plains, Bangladesh), Europe, and the north-eastern USA. These areas have fertile plains, good climate, water, industries and transport.
Sparsely populated regions: hot deserts (Sahara, Arabia), cold regions (northern Canada, Siberia, Antarctica, Greenland), dense equatorial forests (interior Amazon, Congo basin) and high mountains (Himalaya, Andes).
Population density = total population / total land area, expressed as persons per square kilometre.
Factors affecting distribution:
1. Geographical: relief (plains attract people, mountains do not), climate (moderate climates attract), soil (fertile soils support farming), water (rivers and lakes), minerals (mining towns).
2. Economic: industries, jobs, trade and transport attract people to cities.
3. Social and cultural: religious or cultural centres, safety, government policies.

Worked example

(2 marks) A district has a population of 12,00,000 and an area of 800 sq km. Find its population density.

Try it first, then show the solutionSolution

1. Density = population / area - 1 mark.
2. = 12,00,000 / 800 = 1,500 persons per sq km - 1 mark.

Answer: Population density = 12,00,000 / 800 = 1,500 persons per square kilometre.

Factors affecting the population of a place

The population of a place changes because of four factors:
1. Birth rate: the number of live births per 1,000 people in a year.
2. Death rate: the number of deaths per 1,000 people in a year.
3. Immigration: people coming into a place (country or region) to live.
4. Emigration: people leaving a place to live elsewhere.

Natural growth (natural increase) = birth rate - death rate (per 1,000). Natural growth rate in per cent = (birth rate - death rate) / 10.
Population change = (births - deaths) + (immigrants - emigrants).
Net migration = immigrants - emigrants (positive means more people came in).

Why birth rates are high in some places: early marriage, desire for large families (children as helpers or support in old age), low levels of education, especially of women, and limited access to health care and family planning.
Why death rates have fallen: better medical care, vaccination, clean drinking water, sanitation and food supply.

Worked example

(3 marks) A country has a birth rate of 24 and a death rate of 8 per 1,000. (a) Find the natural growth rate in per cent. (b) Is its population increasing or decreasing?

Try it first, then show the solutionSolution

1. Natural increase = 24 - 8 = 16 per 1,000 - 1 mark.
2. Growth rate = 16 / 10 = 1.6 per cent per year - 1 mark.
3. Since births exceed deaths, the population is increasing (if migration is ignored) - 1 mark.

Answer: (a) Natural growth = 24 - 8 = 16 per 1,000 = 1.6 per cent a year. (b) The population is increasing, since births exceed deaths.

Over-population and under-population

These ideas compare population with resources and technology, not just numbers.

Over-population: when a region has more people than its resources (land, water, food, jobs, services) can support at a reasonable standard of living.

• Examples often discussed: Bangladesh, which has one of the highest population densities in the world, and some very crowded cities in developing countries.
• Impact on society: unemployment and poverty; shortage of food, water and housing; overcrowded schools, hospitals and transport; slums; pollution and pressure on forests and land; higher crime and social tension.

Under-population: when a region has fewer people than are needed to make full use of its resources.

• Examples often discussed: Australia and Canada, which have large areas and rich resources but relatively small populations.
• Impact on society: shortage of workers, so resources remain undeveloped; high cost of providing services to scattered people; small markets for industry; dependence on immigrants for labour; in ageing countries, fewer workers to support the elderly.

Optimum population: the size at which people can make the best use of resources and enjoy the highest standard of living with the available technology.
Important: whether a country is over- or under-populated depends on resources and technology. A small, densely populated country with advanced industry and trade may not be over-populated.

Worked example

(4 marks) Distinguish between over-population and under-population with one example each, and give one impact of each on society.

Try it first, then show the solutionSolution

1. Over-population: more people than resources can support - 1 mark.
2. Example: Bangladesh; impact: unemployment, slums, shortage of food and water - 1 mark.
3. Under-population: too few people to use resources fully - 1 mark.
4. Example: Australia or Canada; impact: shortage of workers, undeveloped resources - 1 mark.

Answer: Over-population means more people than the available resources can support at a decent standard of living, as is often discussed for Bangladesh; it leads to unemployment, slums and shortages of food, water and housing. Under-population means too few people to make full use of resources, as in Australia or Canada; it causes shortages of workers and leaves resources undeveloped.

Composition of population: age and sex

Population composition means the structure of a population by characteristics such as age, sex, residence, literacy and occupation.

Age composition: people are divided into three broad groups:

• Young (0-14 years): dependent on others.
• Working age (15-64 years; some sources use 15-59): the economically active group.
• Old (65 years and above; or 60 and above): mostly dependent.

Dependency ratio = (young + old) / working-age population x 100. A high ratio means each worker supports more dependents.

Sex composition is measured by the sex ratio:

• In India, sex ratio = number of females per 1,000 males.
• (Many international sources express it as males per 100 females.)
• India's sex ratio was 943 females per 1,000 males in the 2011 Census.
• A low sex ratio can result from social preference for sons, neglect of girls and female foeticide; in some regions, migration of men for work raises the sex ratio of the villages they leave.

Worked example

(2 marks) A town has 5,000 males and 4,850 females. Find the sex ratio as used in India.

Try it first, then show the solutionSolution

1. Sex ratio = (females / males) x 1,000 - 1 mark.
2. = (4,850 / 5,000) x 1,000 = 970 females per 1,000 males - 1 mark.

Answer: Sex ratio = 4,850/5,000 x 1,000 = 970 females per 1,000 males.

Rural and urban composition

Population is also classified by where people live:

• Rural population: lives in villages; mainly engaged in primary activities such as farming, fishing, forestry and mining.
• Urban population: lives in towns and cities; mainly engaged in secondary (manufacturing) and tertiary (services) activities.

In India, a place is treated as urban by the Census if it is a statutory town (with a municipality or similar body) or meets census criteria such as a minimum population, density and share of male workers in non-farm work.
India: according to the 2011 Census, about 31 per cent of the population lived in urban areas and about 69 per cent in rural areas.
World: since about 2007, more than half of the world's population has lived in urban areas, according to UN estimates.
Why it matters: rural and urban areas need different services; a rising urban share shows industrialisation and migration from villages to towns (see the chapters on migration and urbanisation).

Worked example

(2 marks) In a district of 8,00,000 people, 3,20,000 live in towns. What percentage is urban? Is the district mainly rural or urban?

Try it first, then show the solutionSolution

1. Urban share = 3,20,000 / 8,00,000 x 100 = 40 per cent - 1 mark.
2. Rural share = 60 per cent, so the district is mainly rural - 1 mark.

Answer: 40 per cent of the population is urban (3,20,000/8,00,000 x 100), so 60 per cent is rural and the district is mainly rural.

Population pyramid

A population pyramid (age-sex pyramid) is a graph showing the age and sex composition of a population.

• Horizontal bars represent age groups (usually five-year groups, 0-4, 5-9 and so on), youngest at the bottom.
• Males are shown on the left, females on the right.
• The length of each bar shows the number or percentage of people in that group.

Types:
1. Expanding (expansive) pyramid: wide base and narrow top; high birth rate, high or falling death rate, short life expectancy; a young and growing population. Typical of many developing countries, for example Nigeria.
2. Stationary (constant) pyramid: narrower base and almost equal bars up to older ages; low birth and death rates; slow or no growth.
3. Contracting (constrictive) pyramid: base narrower than the middle; very low birth rate and long life expectancy; an ageing and possibly shrinking population. Typical of countries like Japan.
Uses: planning schools (wide base), jobs (large middle), and pensions and health care (wide top).

Worked example

(3 marks) A country's population pyramid has a very wide base that narrows quickly towards the top. What does this show about (a) its birth rate, (b) its life expectancy, and (c) one need of its government?

Try it first, then show the solutionSolution

1. (a) Wide base: high birth rate, many children - 1 mark.
2. (b) Narrow top: few old people, so life expectancy is low or the death rate was high - 1 mark.
3. (c) Needs: more schools, child health care, future jobs - 1 mark.

Answer: (a) The wide base shows a high birth rate. (b) The narrow top shows that few people reach old age, meaning relatively low life expectancy. (c) The government must provide more schools and child health care, and create jobs for the large young population as it grows up.

Population Dynamics in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• World Population Distribution, Over-population and Under-population
• Birth Rate, Death Rate, Composition and Population Pyramids

Population Dynamics: key facts

Population density

$Density=population/area(personspersqkm)$

Birth and death rates

$Birthrate=births/populationx1,000;deathrate=deaths/populationx1,000$

Per 1,000 people per year.

Natural growth

$Naturalgrowthrate($

Rates per 1,000.

Population change

$Change=(births-deaths)+(immigrants-emigrants)$

Net migration = immigrants - emigrants.

Sex ratio and dependency

$Sexratio(India)=females/malesx1,000;dependencyratio=(0-14+65andabove)/(15-64)x100$

Population Dynamics: map work

The places on the official CISCE map list for this chapter. Find each one on an outline map of India and practise marking it.

How the school exam asks Population Dynamics

The question patterns to expect, and the method that works for each.

Tricks to remember Population Dynamics

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Four doors of population

  Two doors in (births, immigrants), two doors out (deaths, emigrants).

  Use it when: Factors affecting population.

• Pyramid shapes

  'Wide base = baby boom; wide top = grey boom.'

  Use it when: Expanding versus contracting pyramids.

• Growth rate shortcut

  Per 1,000 to per cent: divide by 10.

  Use it when: Natural growth rate.

Population Dynamics: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section B style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 8-mark question split into 3 + 2 + 3 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Population Dynamics

The slips examiners see most often, and what to write instead.

• ✗Mistake: Defining over-population as 'too many people in a country'

  Leaving out resources.

  ✓Do this: Always compare population with resources and the standard of living.

  Usually costs: 1 mark.

• ✗Mistake: Writing the sex ratio as males per 1,000 females for India

  Mixing Indian and international conventions.

  ✓Do this: Indian Census: females per 1,000 males.

  Usually costs: 1 mark.

• ✗Mistake: Forgetting to divide by 10 for growth rate in per cent

  Rates are per 1,000.

  ✓Do this: Per 1,000 to per cent: divide by 10.

  Usually costs: 1 mark.

• ✗Mistake: Ignoring migration in population change

  Only natural increase is calculated.

  ✓Do this: Change = (births - deaths) + (immigrants - emigrants).

  Usually costs: 1-2 marks.

Practice questions on Population Dynamics

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQExam level

   Birth rate is expressed as the number of live births per:
   (a) 100 people
   (b) 1,000 people
   (c) 10,000 people
   (d) square kilometre

   Hint

   Same as death rate.

   Answer

   (b) 1,000 people.

2. Q2 · 1 mark · MCQHarder exam level

   A pyramid with a narrow base and wide top indicates:
   (a) high birth rate
   (b) young population
   (c) ageing population
   (d) high death rate among the old

   Hint

   Few babies, many elderly.

   Answer

   (c) ageing population.

3. Q3 · 1 mark · Very short answerExam level

   What was India's sex ratio in the 2011 Census?

   Hint

   Females per 1,000 males.

   Answer

   943 females per 1,000 males.

4. Q4 · 2 marks · Very short answerHarder exam level

   A village had 900 immigrants and 1,450 emigrants in a year. Find the net migration and state what it means.

   Hint

   In minus out.

   Answer

   Net migration = 900 - 1,450 = -550. It is negative, meaning 550 more people left than came in.

5. Q5 · 2 marks · Very short answerExam level

   Why are the Ganga plains densely populated?

   Hint

   Soil and water.

   Answer

   They have fertile alluvial soil, a plentiful water supply from rivers, flat land suitable for farming and transport, and a long history of settlement.

6. Q6 · 2 marks · Very short answerExam level

   State two impacts of over-population on a city.

   Hint

   Housing and services.

   Answer

   Growth of slums because of housing shortages, and overcrowding of transport, hospitals and schools (also water shortages and pollution).

7. Q7 · 2 marks · Very short answerHOTS / competency

   Why do some parts of Indian villages show a high sex ratio even where girls are not favoured?

   Hint

   Who leaves the village?

   Answer

   Many men migrate to cities for work, leaving more women in the villages, so the number of females per 1,000 males there rises.

8. Q8 · 3 marks · Short answerHarder exam level

   Explain how education of women can reduce the birth rate.

   Hint

   Marriage, health, choices.

   Answer

   Educated women tend to marry later, know more about health and family planning, and often take up paid work. They usually choose to have fewer children and give them better care, so the birth rate falls.

9. Q9 · 2 marks · Very short answerHarder exam level

   Find the dependency ratio of a country where 26 per cent of people are aged 0-14, 66 per cent are 15-64 and 8 per cent are 65 and above.

   Hint

   (26 + 8) / 66 x 100.

   Answer

   (26 + 8)/66 x 100 = 34/66 x 100, about 51.5.

10. Q10 · 4 marks · Long answerHOTS / competency

    Suppose a country's birth rate falls sharply over 30 years while its death rate stays low. Predict two changes in its population pyramid and two effects on society.

    Hint

    Base and top.

    Answer

    Pyramid: the base becomes narrower (fewer children) and the top becomes wider over time (more elderly). Effects: fewer school admissions and, later, fewer young workers; and a rising need for pensions, old-age care and health services, supported by a smaller working population.

11. Q11 · 3 marks · Short answerHarder exam level

    Why do many under-populated countries encourage immigration?

    Hint

    Workers and resources.

    Answer

    They have rich resources and growing industries but too few workers. Immigrants fill job shortages, help develop resources, expand the market and, being mostly young, help support an ageing population.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.What is population density?Show answer

   Number of people per square kilometre.

2. 2.Natural growth rate if BR = 30, DR = 10?Show answer

   (30 - 10)/10 = 2 per cent.

3. 3.What does a wide base in a pyramid show?Show answer

   A high birth rate and a young population.

4. 4.Name a country often cited as under-populated.Show answer

   Australia (or Canada).

5. 5.Which age group is the working age group?Show answer

   15-64 years (some sources use 15-59).

6. 6.What share of India's population was urban in 2011?Show answer

   About 31 per cent.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Distribution uneven: dense in East Asia, South Asia, Europe, NE USA; sparse in deserts, polar lands, rainforests, high mountains.
• ☐Density = population / area. Factors: relief, climate, soil, water, minerals, jobs, transport, culture.
• ☐Change = (births - deaths) + (immigrants - emigrants); natural growth % = (BR - DR)/10.
• ☐Over-population: people exceed resources (Bangladesh often cited) - unemployment, slums, shortages. Under-population: too few to use resources (Australia, Canada) - labour shortage.
• ☐Composition: age (0-14, 15-64, 65+), dependency ratio; sex ratio in India = females per 1,000 males (943 in 2011); rural-urban (about 31% urban in India, 2011).
• ☐Pyramids: expanding (wide base, Nigeria), stationary, contracting (narrow base, Japan).

Population Dynamics: frequently asked questions