IB MYP 4-5 Biology-Human influences- Study Notes - New Syllabus
IB MYP 4-5 Biology-Human influences- Study Notes – New syllabus
IB MYP 4-5 Biology-Human influences- Study Notes – IB MYP 4-5 Biology – per latest IB MYP Biology Syllabus.
Key Concepts:
- Population growth and resource consumption
- Urbanization and land use changes
- Introduction of invasive species
- Climate change impacts
Human Influences: Population Growth and Resource Consumption
1. Human Population Growth
What’s Happening?
The human population has grown rapidly, especially over the last 200 years. In 1800, there were ~1 billion people – now we’re over 8 billion!
Why is the population growing?
- Medical advancements (vaccines, antibiotics)
- Better sanitation and clean water
- Increased food production
- Lower death rates, especially in infants
More births than deaths = population increase
2. Resource Consumption
As population increases, so does demand for natural resources:
| Resource | How Humans Use It |
|---|---|
| Water | Drinking, farming, industries |
| Fossil Fuels | Energy, transport, factories |
| Land | Farming, cities, roads |
| Forests | Wood, paper, land clearing |
| Minerals | Electronics, construction |
Problems Caused by Overconsumption:
Pollution
- Air pollution from vehicles and factories
- Water pollution from chemicals and sewage
- Soil pollution from waste and fertilizers
Climate Change
Burning fossil fuels releases CO₂ → traps heat → global warming.
Habitat Loss
Forests cut for farming/buildings → animals lose homes → biodiversity declines.
Waste Production
More people = more garbage (plastic, e-waste, chemicals).
Ecological Footprint
Real-Life Examples
| Country/Region | Human Impact Example |
|---|---|
| Amazon Rainforest | Cleared for cattle farming & soy crops |
| India | High water use in agriculture |
| USA & China | Largest CO₂ emitters |
| Africa | Rapid urban population growth |
How Can We Reduce Our Impact?
- Use renewable energy (solar, wind)
- Reduce, reuse, and recycle
- Conserve water and electricity
- Eat less meat and waste less food
- Support sustainable development and policies
Human population is growing rapidly, leading to increased use of Earth’s resources.
This causes pollution, climate change, and biodiversity loss.
But with smarter choices, we can build a more sustainable future.
Urbanization and Land Use Changes
What Is Urbanization?
Urbanization is the process where more people move to cities or towns, causing those areas to grow larger. It’s a shift from rural to urban life — driven by jobs, education, and better living standards.
Why Urbanization Happens:
- Population growth
- Industrial development
- Better transport, housing, and services
- Fewer jobs in farming and rural areas
Land Use Changes Explained
| Type of Change | Description |
|---|---|
| Agricultural land → cities | Farms are cleared to build homes and roads |
| Forests → urban zones | Deforestation for housing or industries |
| Wetlands → filled in | To create land for airports, malls, etc. |
| Natural land → paved | Grasslands replaced by concrete and asphalt |
Environmental Impacts of Urbanization
1. Habitat Loss
Animals and plants lose their homes → biodiversity declines
2. Water Issues
More concrete = less water soaks in → flooding, shortages, pollution
3. Urban Heat Islands
Cities are hotter than rural areas due to concrete and less greenery
4. Air and Noise Pollution
Traffic, construction, and factories increase CO₂ and noise levels
5. Loss of Farmland
Cities expand → less local farming → longer food transport = higher emissions
Social & Economic Effects
| Positive Effects | Negative Effects |
|---|---|
| More jobs and businesses | Overcrowding in cities |
| Access to schools and hospitals | Traffic congestion |
| Better infrastructure | Urban-rural inequality |
| Faster emergency services | More pressure on housing & resources |
Real-World Examples
- Mumbai, India: Rapid growth → slums, deforestation
- Amazon region: Forests cleared for urban projects
- Shanghai, China: Wetlands replaced by buildings
Can Urbanization Be Sustainable?
- Green buildings and smart transport
- Urban gardens and green roofs
- Protected parks within cities
- Better waste and water systems
- Spread growth to smaller towns too
Urbanization transforms land from forests and farms into roads and cities.
While it offers better jobs and services, it also causes pollution, biodiversity loss, and water issues.
With smart, sustainable planning, cities can grow without destroying the environment.
Introduction of Invasive Species
What Are Invasive Species?
An invasive species is a non-native organism (plant, animal, or microbe) introduced to a new area where it:
- Survives and spreads rapidly
- Causes harm to the environment, economy, or human health
- Disrupts local ecosystem balance
Not all non-native species are invasive – only those that outcompete or harm native species.
How Are Invasive Species Introduced?
| Method of Introduction | Example |
|---|---|
| Accidental transport | Rats on ships, seeds on boots |
| Intentional release | Garden plants, pets, hunting animals |
| Escape from farms/labs | Fish farms, research facilities |
| Global trade and travel | Ships, planes, cargo goods |
Why Are They a Problem?
1. Outcompete Native Species: Compete for food, light, or space → natives decline
2. Prey on Native Animals: Hunt species with no defenses
3. Spread Diseases: Bring new viruses/parasites
4. Disrupt Ecosystems: Alter food chains, damage soil or water balance
Famous Real-World Examples
| Invasive Species | Location Affected | Impact |
|---|---|---|
| Cane toads | Australia | Poisoned predators, ate native insects |
| Zebra mussels | North American lakes | Clog pipes, damage ecosystems |
| Water hyacinth | India, Africa | Blocks rivers, reduces oxygen |
| Gray squirrels | United Kingdom | Replaced native red squirrels |
| Lantana plant | India, tropics | Chokes native plants |
Why Are They So Successful?
- Few or no natural predators
- Rapid reproduction and spread
- Highly adaptable to new conditions
- Often invade isolated ecosystems (like islands)
How Can We Prevent or Control Them?
Prevention:
- Screen imported goods, ships, and luggage
- Don’t release pets or exotic plants into the wild
- Raise public awareness
Control Measures:
- Physical removal (trapping, culling)
- Chemical control (herbicides/pesticides)
- Biological control (natural predators – used cautiously)
- Habitat restoration to support native species
Invasive species are non-native organisms that spread and harm ecosystems.
They compete with, prey on, or infect native species, leading to loss of biodiversity.
Prevention, control, and education are key strategies to stop their spread.
Climate Change Impacts
What Is Climate Change?
Climate change refers to long-term changes in Earth’s climate, especially rising global temperatures. It’s largely caused by human activities such as burning fossil fuels, which release greenhouse gases (like CO₂ and methane).
Greenhouse Effect
- Sunlight enters Earth’s atmosphere
- Heat gets trapped by greenhouse gases
- More gases = more trapped heat → warming the planet
This process causes global warming – a key part of climate change.
Major Impacts of Climate Change
1. Rising Global Temperatures
- Earth is getting hotter → heatwaves, droughts, wildfires\Affects crops and human health
2. Melting Ice and Glaciers
- Glaciers and polar ice are melting → sea levels rising
3. Sea Level Rise
- Coastal cities face floods, saltwater damages farmland, some areas may become unlivable
4. Extreme Weather
- More powerful storms, floods, and unpredictable rainfall
- Homes and infrastructure get damaged
5. Effects on Wildlife
- Habitats lost (e.g., Arctic animals)
- Migration and breeding cycles disrupted
- Coral reefs bleach in warmer oceans
6. Food and Water Insecurity
- Droughts and floods → crop failures
- Water scarcity → risk of famine
7. Impact on Humans
- Health problems (heatstroke, malaria)
- Climate refugees forced to migrate
- Pressure on resources, housing, jobs
Global Examples
| Impact | Location Example |
|---|---|
| Melting glaciers | Himalayas, Antarctica |
| Coral bleaching | Great Barrier Reef, Australia |
| Floods and storms | Bangladesh, Philippines |
| Drought and crop loss | Sub-Saharan Africa, Central India |
| Wildfires | California (USA), Australia |
What Can Be Done?
Reduce Greenhouse Gases:
- Use renewable energy (solar, wind)
- Drive less, recycle more, plant trees
- Make homes and devices energy-efficient
Prepare and Adapt:
- Build stronger flood defences
- Grow drought-resistant crops
- Educate and create climate policies
Summary Table
| Effect | Cause | Result |
|---|---|---|
| Global warming | Greenhouse gas emissions | Hotter climate |
| Melting ice caps | Rising temperatures | Sea level rise |
| Extreme weather | Ocean warming, unstable air | Floods, cyclones |
| Loss of biodiversity | Habitat loss & warming | Species extinction |
| Food & water shortages | Drought, crop failure | Hunger, conflict |
Climate change is real and global.
It causes hotter temperatures, extreme weather, sea level rise, and harms both nature and people.
But with clean energy, better planning, and global cooperation, we can reduce its impact.