IB Environmental systems and societies Topic 8.1C Age-sex Pyramids and Demographic Transition Model Revision Notes (SL/HL)

IB Environmental systems and societies Topic 8.1C Age-sex Pyramids and Demographic Transition Model Revision Notes (SL/HL) | RevisionDojo

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Age-Sex Pyramids: Reading a Population's Past and Future

Definition

Age-sex pyramid

An age-sex pyramid visually represents the composition of a population by age groups and gender.

How to Read an Age-Sex Pyramid

The x-axis shows population size, as an absolute number or a percentage.
The y-axis shows age groups, usually in 5-year cohorts.
The left side shows males and the right side shows females.
The overall shape reveals birth rate, death rate, and life expectancy at a glance, which is why pyramids let you compare societies and predict future trends.

The Three Pyramid Shapes and What They Mean

Expanding (youthful population)
1. A broad base and narrow top signal a high birth rate and lower life expectancy.
2. Common in lower-income countries such as Nigeria and Afghanistan.
3. It strains schools, healthcare, and food supply.
Stationary (stable population)
1. Straighter sides with fairly even cohorts until old age.
2. Birth and death rates are moderate and near replacement level.
3. Seen in high-income countries such as the USA and France.
Contracting (ageing population)
1. A narrow base and wide top signal a low birth rate and high life expectancy.
2. Common where populations are shrinking, such as Japan and Germany.
3. It strains pensions and elderly care as the workforce shrinks.

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

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Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Age-Sex Pyramids: Reading a Population's Past and Future

Definition

Age-sex pyramid

An age-sex pyramid visually represents the composition of a population by age groups and gender.

How to Read an Age-Sex Pyramid

The x-axis shows population size, as an absolute number or a percentage.
The y-axis shows age groups, usually in 5-year cohorts.
The left side shows males and the right side shows females.
The overall shape reveals birth rate, death rate, and life expectancy at a glance, which is why pyramids let you compare societies and predict future trends.

The Three Pyramid Shapes and What They Mean

Expanding (youthful population)
1. A broad base and narrow top signal a high birth rate and lower life expectancy.
2. Common in lower-income countries such as Nigeria and Afghanistan.
3. It strains schools, healthcare, and food supply.
Stationary (stable population)
1. Straighter sides with fairly even cohorts until old age.
2. Birth and death rates are moderate and near replacement level.
3. Seen in high-income countries such as the USA and France.
Contracting (ageing population)
1. A narrow base and wide top signal a low birth rate and high life expectancy.
2. Common where populations are shrinking, such as Japan and Germany.
3. It strains pensions and elderly care as the workforce shrinks.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 8.1C Age-sex Pyramids and Demographic Transition Model Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Age-Sex Pyramids: Reading a Population's Past and Future

How to Read an Age-Sex Pyramid

The Three Pyramid Shapes and What They Mean

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Age-Sex Pyramids: Reading a Population's Past and Future

How to Read an Age-Sex Pyramid

The Three Pyramid Shapes and What They Mean

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account