Describe biodiversity and habitat loss
Biodiversity describes the number of different species living in an area; habitat destruction removes or changes the places those species depend on.
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Know that organisms interact with other organisms and their environment.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
In this syllabus, what does biodiversity measure?
What you will learn
- Define biodiversity as the number of different species living in an area
- Explain how land use, resource extraction and pollution can destroy habitats
Measure species variety and identify causes
For this syllabus, biodiversity is the number of different species that live in an area. It is about variety of species, not simply the total number of individual organisms. A survey that finds more species in one comparable area has recorded greater biodiversity.
Habitats can be destroyed or reduced when land is converted for housing, crop production or livestock production, when natural resources are extracted, and when freshwater or marine environments are polluted. One activity can have more than one effect: clearing land for a mine, for example, removes habitat and extracts a resource.
Keep cause and consequence linked
Describe a human activity first, then state how it changes or removes a habitat. Pollution can make water or land unsuitable for organisms; construction and production replace or fragment living areas; extraction disturbs the habitat and removes materials. Use the context given rather than assuming every project has identical effects.
A species count is meaningful when the areas were sampled in comparable ways. Different sampling effort can change the number found, so conclusions about biodiversity should note the area and method.
Sources for this lesson
Pause and explain
Which is a stated reason for habitat destruction?
Worked example
A survey records 12 species in a wetland before drainage and 7 species afterwards. What biodiversity change is supported by these counts?
Show the worked solution
- Compare the number of different species recorded in each survey.
- The counts concern species variety, not the total number of animals.
Answer The later survey recorded five fewer species, so the recorded biodiversity was lower. A fair comparison assumes similar area and sampling effort.
Try a topic test
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Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
An area contains 15 plant and animal species in one survey and 9 in a later comparable survey. State what changed.
Give me a hint
Compare the species counts, not individual abundance.
Compare my reasoning
- The later count is lower.
- 15 − 9 = 6 fewer species were recorded.
The survey recorded six fewer different species, so measured biodiversity decreased in that comparison.
Look for these in your work
- Difference correct
- Biodiversity measure interpreted
Give three syllabus-linked causes of habitat destruction.
Give me a hint
Think about land use, extraction and pollution.
Compare my reasoning
- Housing, crop or livestock production can use habitat land.
- Natural-resource extraction and freshwater or marine pollution are also causes.
Habitat destruction can result from land used for housing, crop or livestock production, extraction of natural resources, and pollution of freshwater or marine environments.
Look for these in your work
- Three causes named
- Causes are syllabus-linked
A coastal area is polluted and a nearby forest is cleared for a road. Explain how these are different habitat pressures.
Give me a hint
Identify the setting and the activity in each case.
Compare my reasoning
- Pollution changes the marine environment.
- Clearing for a road removes or fragments forest habitat.
Marine pollution can make the coastal habitat unsuitable for some organisms; road construction clears or fragments the forest habitat. Both can reduce available living space, by different routes.
Look for these in your work
- Each pressure identified
- Habitat effect explained
Common mistakes
- Defining biodiversity as the number of individual organisms
- Treating every change in land use as an identical effect
- Comparing surveys with very different sampling effort without qualification
What can you explain now?
In this syllabus, what does biodiversity measure?
Compare with the explanation
The number of different species living in an area
This is the required definition.
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Make it stick
Define biodiversity and name the three broad human activities in this section that can destroy habitats.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.