ENVIRONMENTAL SCIENCE REVISION
MODULE 2
Demographics
Demographics refers to statistical data about the characteristics of a population ( study of
populations). It helps us understand different groups of people based on factors such as:
Age (e.g., children, adults, seniors)
Gender (male, female, other identities)
Income level (low, middle, high income)
Education level (primary, secondary, university)
Occupation (students, professionals, retirees)
Religion (Christianity, Islam, Hinduism, etc.)
Ethnicity (racial and cultural backgrounds)
Marital status (single, married, divorced)
Abiotic and Biotic Factors That Affect Population Distribution and
Activities
The distribution of populations (where organisms live and how they interact in an environment)
is influenced by two types of factors:
1️. Biotic Factors (Non-living)
These are physical and chemical environmental conditions that impact population distribution
and activities.
Climate – Temperature, rainfall, and sunlight affect where organisms can survive. Example:
Cacti thrive in hot deserts, while polar bears live in cold regions.
Water Availability – Essential for all living things. Areas with more freshwater (rivers,
lakes) support larger populations of plants, animals, and humans.
Soil Type & Nutrients – Fertile soils support plant growth, influencing herbivores and
predators in the food chain. Poor soils limit plant populations.
Light Intensity – Affects photosynthesis in plants, influencing food supply for herbivores
and carnivores.
Altitude & Terrain – Mountains have fewer populations due to cold temperatures and low
oxygen, while plains support more life due to better conditions.
Natural Disasters – Hurricanes, droughts, and earthquakes can decrease populations by
destroying habitats.
2️. Biotic Factors (Living)
These are interactions between organisms that affect their distribution and survival.
Predation – If predators are too many, prey populations decrease, affecting the food chain.
Example: Wolves controlling deer populations.
Competition – Organisms compete for resources like food, space, and mates. Example:
Lions and hyenas competing for prey in the savanna.
Food Availability – The presence of abundant food sources attracts and supports larger
populations. Example: Coral reefs have rich marine life due to food supply.
Disease & Parasites – Can reduce populations if infections spread quickly. Example:
Malaria affects human population growth in tropical regions.
Human Activities – Farming, deforestation, and urbanization can either increase or decrease
populations. Example: Deforestation reduces habitats for birds and other animals.
Demographic Characteristics of Human Populations
Demographics refer to the statistical study of human populations, including their size, structure,
and distribution. The key demographic characteristics include:
1️. Population Size & Density
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Population Size: The total number of people in a specific area.
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Population Density: The number of people living per square kilometer or mile.
o
High Density: Found in cities like Kingston, Jamaica.
o
Low Density: Found in rural areas with fewer people.
2️. Age Structure
•
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Divides the population into age groups:
o
Young (0-1️4 years) – High in developing countries.
o
Working-age (1️5-64 years) – Supports the economy.
o
Elderly (65+ years) – Requires healthcare and support.
A population with more young people is growing, while one with more elderly people is
aging.
3️. Birth Rate & Death Rate
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Birth Rate: Number of live births per 1,000 people per year.
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Death Rate: Number of deaths per 1,000 people per year.
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Natural Increase: If the birth rate is higher than the death rate, the population grows.
4. Migration (Immigration & Emigration)
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Immigration: People moving into a country.
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Emigration: People moving out of a country.
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Migration affects population growth and workforce availability.
5. Gender Composition
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The ratio of males to females in a population.
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Some regions have more females due to longer life expectancy, while some have more
males due to birth ratios.
6. Education & Literacy Rate
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The percentage of the population that can read and write.
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Higher literacy leads to better job opportunities and economic development.
7️. Employment & Economic Status
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Number of people working and their types of jobs (agriculture, industry, services).
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Affects income levels and quality of life.
8️. Health & Life Expectancy
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Life Expectancy: The average number of years a person is expected to live.
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Infant Mortality Rate: The number of babies that die before their first birthday per
1,000 births.
•
Good healthcare increases life expectancy and lowers mortality rates.
Doubling Time: This is the amount of time it will take a population to double in size.
WHY IS THE 7️0 USED IN DOUBLING TIME FORMULA?
CALCULATIONS
Population Growth Rate Calculation
Scenario: You want to calculate the annual population growth rate of a city over the past 5
years.
Example:
•
Population in 2️02️0: 1️,000,000
•
Population in 2️02️5: 1️,2️00,000
Outcome: The population has grown by 2️0% over the 5 years.
Replacement fertility rate is the number of children that is expected to replace their
parents.
PER CAPITA
Per capita is a Latin term that translates to "per person." It is used in demographics,
economics, and other fields to provide an average or rate for each individual in a
population.
EXAMPLE
Comparison Between Historical Trends and Current trends in population Growth
Characteristics
Historical Trends
Current Trends
Poverty- The state of being poor.
Characteristic
Relative Poverty
Absolute
Acute ( most severe of
the 3️)
AGE STRUCTURE PYRAMIDS
Population Control Measures:
(i)
(ii)
Direct - Family Planning measures and methods, government policies
Indirect - Natural disasters (floods, earthquakes, volcanoes, hurricanes.
INDICES USED TO MEASURE POVERTY
1️. Access to Education
2️. Access to Health Care
3️. Access to Basic needs
HDI and GDI
The Human Development Index (HDI) and the Gender Development Index (GDI)
are both measures used to assess the well-being and development of countries, but
they focus on different aspects.
1️.
HDI (Human Development Index):
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Measures overall human development in a country.
•
It considers three key dimensions:
•
Life expectancy (health)
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Education (mean years of schooling and expected years of schooling)
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Standard of living (income or Gross National Income per capita)
GDI (Gender Development Index):
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Measures the gender gap in human development.
•
It is derived from the HDI, but it adjusts for gender disparities.
•
GDI compares the HDI of women to the HDI of men in a country,
reflecting the differences in achievements between genders in terms of health,
education, and income.
What does is mean when a country score a low HDI score?
The lower HDI (Human Development Index) reading indicates lower levels of
human development in a country. Specifically, it means that the country.
MODULE 3️ RESOURCES
CONSUMPTIVE AND NON CONSUMPTIVE RESOURCES DIFFERENCE