6.1.3Global Challenges
Maintaining Biodiversity — OCR Gateway GCSE Combined Science A J250 - Biology Revision Notes & Topical Questions
5 min read 9 parts Lesson 4 of 18
Section 1 of 9Why action is needed
Human activities have reduced biodiversity worldwide, and many species are endangered. Scientists, conservation groups and governments therefore work to protect species and habitats. Some of the actions involve breeding programmes and legal protection; others involve changes to how land is farmed and how waste is handled. The aim is to keep ecosystems stable and to maintain resources for the future.
Section 2 of 9Protecting species and habitats
- Seed banks store seeds of rare plants.
- and farmers are encouraged to leave strips for wildlife; these create corridors and food sources.
Reintroduction programmes release captive-bred animals into protected areas, and the new population is monitored with tags or surveys. Organisations also remove invasive species that out-compete native ones, for example by trapping or by managing grazing so that rare plants are not overwhelmed. Such practical work is usually done by trained staff and volunteers.
Section 3 of 9Laws and agreements
Governments pass laws that limit hunting, fishing and trade in endangered species, and international agreements set limits on emissions and protect certain regions. Laws need to be enforced to work, which requires money and monitoring. Some schemes pay local people to look after habitats, so conservation provides jobs as well as protecting wildlife.
Section 4 of 9Making decisions: costs and benefits
Conservation has costs.
| Scheme | Benefit | Difficulty |
|---|---|---|
| Zoo breeding | Raises numbers of rare species | Costly; may not find habitat for release |
| Hedgerow replanting | Creates habitat and corridors | Takes land from crops |
| Seed bank | Preserves genes of rare plants | Does not keep the habitat |
| Recycling | Cuts waste and pollution | Needs sorting and public cooperation |
Because resources are limited, conservationists have to decide which species and habitats to prioritise, often choosing those that are most threatened or that protect many other species at once.
Section 5 of 9Trade-offs in practice
There is rarely a perfect solution. Protecting a forest might reduce income from timber; reducing cattle numbers would cut methane but also affects food supply. Scientists provide evidence, but decisions are made by people balancing environmental, economic and social concerns. Public awareness and education encourage individuals to support conservation through their choices as consumers.
When evaluating schemes in the exam, link each measure to the exact biological effect it has. For example, hedgerows provide shelter and nesting sites and link woods so that small mammals can move between them, which increases the gene flow between populations and so improves their long-term survival.
Section 6 of 9Case studies and monitoring
Practical examples show how programmes work.
- and the surplus then spills into nearby waters, helping fishermen as well.
Programmes need to be monitored to see whether they work. Scientists count populations in the same places each year using standard sampling methods, compare reserves with unprotected areas and check that the genetic variety of captive populations remains high. If results show that numbers are not recovering, the strategy can be changed.
Successful conservation usually involves local people. If villagers are paid as rangers or guides, or can share income from tourism, they have a reason to protect the wildlife rather than hunt it. Schemes imposed without consultation are more likely to fail.
Section 7 of 9Exam-style questions
Evaluate the use of captive breeding to protect an endangered species. [4]4 marks
Advantage: numbers can be increased in a safe environment, protected from predators and habitat loss [1]; animals may be reintroduced to the wild [1]. Disadvantage: expensive [1]; small gene pool/inbreeding may reduce genetic variety, and suitable habitat may no longer exist for release [1].
Suggest why farmers may be reluctant to leave field margins uncultivated. [2]2 marks
Less land is used for crops, so there is less yield and income [1]; they may fear weeds and pests spreading into the crop [1].
State two reasons why recycling helps to maintain biodiversity. [2]2 marks
Less waste goes to landfill, so less land is used and less pollution is produced [1]; fewer raw materials are extracted from habitats, such as through quarrying or logging [1].
Section 8 of 9Key terms
| Term | Meaning |
|---|---|
| Conservation | Protecting and managing species and habitats. |
| Captive breeding | Breeding endangered species under human care to increase numbers. |
| Seed bank | A store of seeds from many plant species to preserve their genes. |
| Nature reserve | A protected area where wildlife is managed. |
| Hedgerow | A line of shrubs and trees between fields that provides habitat. |
| Endangered | At risk of becoming extinct. |
Section 9 of 9Exam technique
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