Edexcel iGCSE Biology-5.12 Biological Consequences of Air Pollution- Study Notes- New Syllabus
Edexcel iGCSE Biology-5.12 Biological Consequences of Air Pollution- Study Notes- New syllabus
Edexcel iGCSE Biology-5.12 Biological Consequences of Air Pollution- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
5.12 understand the biological consequences of pollution of air by sulfur dioxide and carbon monoxide
Air Pollution: Sulfur Dioxide & Carbon Monoxide
🔹 Introduction
Air pollution has serious biological effects on humans, animals, and the environment.
Two major harmful gases are:
Sulfur dioxide (SO₂) → from burning fossil fuels.
Carbon monoxide (CO) → from incomplete combustion of fuels.
1. Sulfur Dioxide (SO₂)
- Sources
• Burning coal, oil, and gas in power stations, factories, vehicles.
• Industrial processes like metal smelting. - Biological Consequences
- In humans: Irritates lungs & throat → coughing, asthma, bronchitis. Long-term exposure → lung diseases.
- In plants: Dissolves in rain → acid rain (H₂SO₃/H₂SO₄). Damages leaves, reduces photosynthesis, leaches minerals (Ca, Mg) → poor soil fertility.
- In environment: Acidifies rivers/lakes → kills fish. Damages limestone/marble buildings and monuments.
2. Carbon Monoxide (CO)
- Sources
• Incomplete combustion of fuels in car engines, stoves, heaters.
• Cigarette smoke. - Biological Consequences
- In humans/animals: CO binds to haemoglobin (Hb) 200× stronger than O₂ → forms carboxyhaemoglobin → prevents O₂ transport.
Effects: headaches, dizziness, fatigue. Severe → brain damage, unconsciousness, death.
Dangerous for pregnant women → reduces O₂ to foetus. - In environment: Contributes to poor air quality. Indirectly worsens global warming (affects methane breakdown).
- In humans/animals: CO binds to haemoglobin (Hb) 200× stronger than O₂ → forms carboxyhaemoglobin → prevents O₂ transport.
📊 Comparison Table
| Gas | Source | Biological Consequences in Humans | Effects on Plants/Environment |
|---|---|---|---|
| Sulfur dioxide (SO₂) | Burning fossil fuels, industries | Respiratory issues: asthma, bronchitis, lung irritation | Acid rain damages plants, acidifies lakes, corrodes buildings |
| Carbon monoxide (CO) | Incomplete combustion (cars, stoves, cigarettes) | Binds with Hb → blocks O₂ transport → suffocation risk | Contributes to pollution, affects methane cycle |
📝 Quick Recap
SO₂ → acid rain, respiratory issues, damages plants, lakes, and buildings.
CO → binds haemoglobin → blocks O₂ transport → toxic, deadly, reduces foetal oxygen supply.
Both → major pollutants, harmful to health and environment.