AQA GCSE Combined Science Foundation (8464), Foundation tier · Biology › Ecology › Biodiversity and the effect of human interaction on ecosystems
Practise Waste management. 5 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
A growing human population with a rising standard of living uses more resources and makes more waste, which can pollute water, air and land. Expect questions on the sources of pollution and how pollution reduces biodiversity, often with data.
Key facts
More people + higher standard of living → more resources used → more waste
Water pollution: sewage, fertiliser, toxic chemicals
Air pollution: smoke, acidic gases
Land pollution: landfill, toxic chemicals
Pollution kills plants and animals → lower biodiversity
Acidic gases (e.g. sulfur dioxide) → acid rain
Notes
Why there is more waste
The human population is growing rapidly and the standard of living is increasing.
So more resources are used and more waste is produced.
If waste and chemicals are not dealt with properly, pollution increases.
Where pollution happens
Water: from sewage, fertiliser and toxic chemicals.
Air: from smoke and acidic gases.
Land: from landfill and toxic chemicals.
Pollution kills plants and animals, which can reduce biodiversity.
Examples of the effects
Acidic gases, such as sulfur dioxide from burning fuels, dissolve in rainwater to make acid rain. This damages trees and can make lakes and rivers too acidic for many organisms.
Smoke contains tiny solid particles that can harm the lungs of animals and coat leaves, reducing photosynthesis.
Landfill takes up land that could be a habitat, and toxic chemicals can leak from it into the soil and water.
Toxic chemicals, such as pesticides, can kill organisms other than the pests they are meant to kill.
How to answer each type of question
Recall: name a source of pollution
1 to 3 marksGrade 3
Match the source to where it pollutes: water, air or land.
Be specific: 'fertiliser' or 'sewage', not just 'waste'.
Example. Give one source of pollution for each of: (a) water (b) air (c) land.
Link both to more resources used and more waste made.
Example. Explain why the amount of waste produced by humans has increased over the last 100 years.
Show the model answerHide the model answer
The human population has increased rapidly (1). The standard of living has increased, so each person uses more resources and produces more waste (1).
Describe and explain pollution data
2 to 3 marksGrade 5
Describe the pattern with numbers.
Link the pollutant to the number of organisms or species.
Explain using the chain of effects.
Example. Scientists counted the invertebrate species in samples taken from a river at three sites near a sewage outlet.
Sampling site
Number of invertebrate species
Upstream of the outlet
14
100 m downstream
3
1 km downstream
9
Describe and explain the pattern. (3 marks)Show the model answerHide the model answer
The number of species is lowest 100 m below the outlet (3 species), compared with 14 upstream and 9 at 1 km downstream (1). Bacteria break down the sewage and their respiration uses up oxygen, so fewer species can survive just below the outlet (1). Further downstream the sewage has been diluted or broken down, so there is more oxygen and more species survive (1).
Don’t lose marks
Saying fertiliser 'poisons' the fish. The fish die from lack of oxygen, used up by respiring decomposers.
Saying the plants die from lack of oxygen. Plants below the surface die from lack of light; it is the animals that die from lack of oxygen.
Writing 'pollution' or 'waste' without naming a specific source.
Forgetting to link back to biodiversity: pollution kills organisms, so there are fewer species.
the standard of living has increased, so each person uses more resources
(e)
it kills plants and animals
Question 2Medium6 marks
Burning coal in power stations releases acidic gases such as sulfur dioxide. These gases dissolve in rain water. Scientists measured the pH of the water in lakes in one region and counted the number of fish species in each lake. {table} shows the results.
[object Object]
(a) Describe the relationship shown in {table}.[1]
(b) Suggest why fewer species of fish live in more acidic lakes.[2]
(c) Acidic gases released in one country can reduce biodiversity in another country. Suggest why.[1]
(d) Explain why rapid growth in the human population can lead to more pollution.[2]
Show the answer and mark scheme
(a)
as the pH decreases (more acidic), the number of fish species decreases
(b)
some species cannot survive at low pH (e.g. the acid damages gills / kills eggs)
enzymes in the fish may be denatured at low pH
the plants and invertebrates that fish eat are killed, so there is less food
(c)
the gases are carried by the wind / clouds and fall as acid rain in other countries
(d)
more people use more resources / burn more fuel
(so) more waste / pollutants are produced, which cause pollution unless handled properly