Introduction: Pollution in Biology (WAEC Syllabus)
Pollution is a major environmental topic in WAEC Biology. It refers to the introduction of harmful substances into the environment, leading to negative effects on humans, animals, plants, and ecosystems.
WAEC often tests your ability to:
- Identify types of pollution
- Explain causes and effects
- Suggest control and preventive measures
- Understand the consequences of poor waste management
This post combines WAEC-style past questions with a short revision guide to make your reading more effective.
Quick Revision Notes on Pollution
- Pollution is classified by the type of environment affected:
- Air Pollution – caused by smoke, gases, dust (e.g., from vehicles, industries)
- Water Pollution – caused by sewage, oil spills, chemicals
- Soil Pollution – caused by solid waste, pesticides
- Noise Pollution – from loud machines, traffic, music
- Common pollutants include:
- Carbon monoxide (CO)
- Sulphur dioxide (SO₂)
- Nitrogen oxides
- Plastics and non-biodegradable materials
- Health Effects:
- Respiratory problems
- Waterborne diseases
- Cancer and skin irritation
- Death of aquatic life
- Control Measures:
- Recycling
- Waste treatment
- Laws against dumping
- Use of clean energy
WAEC Past Questions on Pollution
1. Which of the following gases is a major cause of acid rain?
A. Oxygen
B. Carbon dioxide
C. Sulphur dioxide
D. Nitrogen
2. One major effect of water pollution is:
A. Earthquake
B. Flooding
C. Death of aquatic organisms
D. Deforestation
3. Which of these is a biodegradable pollutant?
A. Plastics
B. Glass
C. Vegetable peels
D. Polythene bags
4. Which of the following is not an effect of air pollution?
A. Respiratory problems
B. Acid rain
C. Ozone layer destruction
D. Soil fertility
5. The major source of water pollution in urban areas is:
A. Animal droppings
B. Untreated sewage
C. Crop residues
D. Tree leaves
6. What is the best method of controlling noise pollution?
A. Using insecticides
B. Using earplugs
C. Building soundproof walls
D. Planting trees
7. The term “non-biodegradable” refers to materials that:
A. Decay easily
B. Can be eaten by animals
C. Cannot decompose naturally
D. Are always useful to plants
8. One effective way to reduce air pollution is to:
A. Increase factory production
B. Ban the use of public transport
C. Promote the use of clean energy
D. Spray more insecticides
9. Which pollutant is most commonly associated with vehicle emissions?
A. Lead
B. Nitrogen
C. Carbon monoxide
D. Chlorine
10. A good waste disposal method in rural areas is:
A. Open dumping
B. Incineration
C. Composting
D. Landfilling
Get full questions below…
Exam Tip:
WAEC loves to ask questions on types, causes, and effects of pollution. Make sure to:
- Memorize examples of pollutants and their sources
- Know which pollutant causes which problem
- Be ready to suggest control measures for each pollution type
OBJECTIVES
Use the substances listed below to answer questions 1 & 2.
I. Fertilizer
II. Insecticides
III. Sewage
IV. Crude oil
V. Sulphur dioxide.
1. The atmosphere can be polluted by
A. I only. B. Ill only. C. IV only. D. II and V only.
2. Which of the substances constitute domestic waste?
A. I only. B. III only. C. IV only. D. II and V only.
3. The use of water closet and septic tanks is preferred to the use of bucket and pit latrines because
A. it is cost effective. B. contaminated faeces are completely kept away from flies. C. the water for flushing contains chlorine which kills the germs. D. it prevents flies from breeding.
4. The detection of Vibrocholerae in public drinking water is a sign of
A. clean water. B. outbreak of disease. C. water pollution. D. decayed organisms in the water.
5. Oil applied to the surface of water kills the larvae of mosquitoes through
A. dehydration. B. poisoning. C. starvation. D. suffocation.
The diagram below shows the effect of nitrates water bodies. Study it carefully and answer question 6 & 7
6. The phenomenon in the diagram is termed
A. denitrification. B. conservation. C. eutrophication D. global warming.
7. Another cause that could lead to the phenomenon in the, diagram is
A. exhaust from cars. B. oil spillage. C. dumping of sewages. D. excess rainfall.
8. The major pollutant around airport residential areas is
A. oil spillage. B. soot. C. noise. D. dust.
9. The following are greenhouse gases except
A. carbondioxide. B. chlorofluorocarbon. C. methane. D. oxygen.
The diagram below shows the oxygen level, number of green plants and fish in rivers flowing through four towns
| Town | Oxygen Level | Green Plants | Fish |
| A | High | Few | Many |
| B | Low | Many | Many |
| C | High | Few | Few |
| D | Low | Many | Few |
10. Which of the towns is likely to be discharging untreated sewage in their river?
A. B. C. D.
11. Which of the following materials is not easily biodegradable?
A. Polythene bag B. Cotton bag C. Hides and skin bag D. Paper bag.
12. Which of the following is not a way of reducing air pollution?
A. Siting factories and power stations away from residential areas. B. Building tall factory chimneys. C. Passing waste gases through filters and absorbers. D. Recycling tins, cans and bottles.
13. Which of the following water pollutants may contain organisms that cause dysentery?
A. Pesticides. B. Sewage. C. Industrial wastes. D. Fertilizers.
14. Which of the following may not contribute to environmental pollution?
A. Solar energy radiation. B. Industrial wastes. C. Waste disposal. D. Smoke.
15. A constituent of the exhaust gases of motor Vehicles which causes serious air pollution is
A. water vapour. B. carbondioxide. C. carbonmonoxide. D. oxygen.
16. Algal bloom depletes oxygen content of bodies of water polluted by
A. industrial effluents. B. thermal plant discharge. C. raw sewage disposal. D. crude oil spillage.
17. Conventional method of sewage disposal involves allthe following except defecating
A. into pit latrines. B. inopen fields. C. into cesspit. D. into bucket latrine.
18. Which of the following is a pollutant of air?
A. Oxygen. B. Water vapour. C. Carbon monoxide. D. Nitrogen.
19. Which of the following is not a pollution control measure?
A. Penalising those who dump refuse on water or land. B. Controlling the emission of smoke from automobiles and industries. C. Ensuring that there is no spillage of oil. D. Channeling sewage into streams.
20. Air pollution can be reduced by the following methods except
A. building tall factory chimneys. B. passing waste gases through filters and absorbers. C. using lead-free petrol in cars. D. recycling tins cans and bottles.
21. Improper sewage disposal could be dangerous for the following reasons except
A. the smell of carelessly disposed sewage water is most undesirable. B. the spread of gastro-intestinal diseases are enhanced. C. resultant out-break of water-borne diseases D. there would be little space for disposal of waste.
22. The depletion of the ozone layer will result in the earth surface receiving more
A. Gamma rays. B. Infra-red rays. C. Ultraviolet rays. D. X-rays.
Theory
1. (a) What is pollution?
(b) State four pollutants of water.
(c) Describe the effects of each of the pollutants named on aquatic organisms.
2. (a) State three sources of noise pollution.
(b) List two ways by which noise pollution can be reduced.
(c) State three effects each of the following pollutants on humans:
(i) smoke
(ii) sewage.
3. (a) What is sewage?
(b) State five effects of releasing untreated sewage into a stagnant water body.
4. (a) What is Eutrophication?
(b) State two causes of eutrophication.
5. (a) What is Pollution?
(b) Name two pollutants each of air and water
(c) State four effects of water pollution on organisms
(d) Mention four ways of preventing water pollution in an environment
(e) Name three sources of noise pollution
(f) State three effects of noise pollution on man.
6. (a) State eight human activities that may pollute water bodies
(b) Explain the measures that may be used to prevent pollution of water bodies.
(c) Mention four methods of purifying water.
7. (a) What is pollution?
(b) State six human activities which cause pollution.
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