20.4 Conservation
- Syllabus
- 0610–2026–2027
- Topic
- 20.4
- Level
- —
Learning objectives
20.4.1Sustainable resource as one which is• Describe a sustainable resource as one which is produced as rapidly as it is removed from the environment so that it does not run out20.4.2Some resources can be conserved• State that some resources can be conserved and managed sustainably, limited to forests and fish stocks20.4.3Organisms become endangered or extinct• Explain why organisms become endangered or extinct, including: climate change, habitat destruction, hunting, overharvesting, pollution and introduced species20.4.4Endangered species can be conserved• Describe how endangered species can be conserved, limited to: (a) monitoring and protecting species and habitats (b) education (c) captive breeding programmes (d) seed banks20.4.5Forests can be conserved using• Explain how forests can be conserved using: education, protected areas, quotas and replanting20.4.6Fish stocks can be conserved using• Explain how fish stocks can be conserved using: education, closed seasons, protected areas, controlled net types and mesh size, quotas and monitoring20.4.7Reasons for conservation programmes• Describe the reasons for conservation programmes, limited to: (a) maintaining or increasing biodiversity (b) reducing extinction (c) protecting vulnerable ecosystems (d) maintaining ecosystem functions, limited to nutrient cycling and resource provision, including food, drugs, fuel and genes20.4.8Use of artificial insemination (AI)• Describe the use of artificial insemination (AI) and in vitro fertilisation (IVF) in captive breeding programmes20.4.9Risks to a species if its population• Explain the risks to a species if its population size decreases, reducing genetic variation (knowledge of genetic drift is not required)
Define a sustainable resource by replacement rate
A sustainable resource is produced as rapidly as it is removed from the environment, so it does not run out.
The test is a rate comparison: replacement rate must be at least equal to removal rate. If removal is faster, the stock decreases and use is not sustainable.
A resource is not sustainable merely because it is natural or causes little pollution. Its rate of replacement must match its rate of use.
Recognise forests and fish stocks as manageable resources
Forests and fish stocks are biological resources that can be conserved and managed sustainably.
| Resource | Basis for sustainable management |
|---|---|
| forests | trees can regrow or be replanted while removal is controlled |
| fish stocks | fish reproduce while catches are controlled so the population can replace removals |
Sustainable management does not mean no use. It means controlling use so replacement can keep pace with removal.
Explain six causes of endangerment and extinction
A species becomes endangered when its population falls so low that extinction becomes likely; extinction occurs when no members remain.
| Cause | How it lowers population survival |
|---|---|
| climate change | conditions and habitats shift faster than some species can adapt or move |
| habitat destruction | food, shelter and breeding sites are removed |
| hunting | individuals are killed faster than they are replaced |
| overharvesting | too many organisms are removed for populations to recover |
| pollution | toxins or changed environmental conditions reduce survival or reproduction |
| introduced species | new predators, competitors or pathogens harm native populations |
A cause must be linked to reduced survival or reproduction. Endangered means at high risk; extinct means the species has no living individuals.
Match endangered-species conservation methods to roles
Conservation combines information, protection, behaviour change and stored or captive populations.
| Method | Conservation role |
|---|---|
| monitoring species and habitats | reveals population trends, locations and threats |
| protecting species and habitats | reduces killing and preserves food, shelter and breeding sites |
| education | changes behaviour and builds support for sustainable practices |
| captive breeding programmes | increase numbers under protection and can supply individuals for reintroduction |
| seed banks | store seeds from plant species for future growth and preserve genetic material |
Captive breeding and seed banks support wild conservation; they do not remove the need to protect the original habitat.
Explain four ways to conserve forests
Forest conservation controls removal, protects habitat and replaces harvested trees.
| Method | How it conserves forests |
|---|---|
| education | reduces damaging practices and supports sustainable use |
| protected areas | restrict clearance and safeguard habitats |
| quotas | limit the amount of timber removed so regrowth can keep pace |
| replanting | replaces harvested trees and restores forest cover |
Replanting alone is insufficient if trees are still removed faster than they grow. Conservation depends on replacement and controlled removal together.
Explain six ways to conserve fish stocks
Fish-stock management must leave enough breeding adults and young fish for reproduction to replace the catch.
| Method | How it protects the stock |
|---|---|
| education | reduces demand for unsustainable catches and improves compliance |
| closed seasons | prevents fishing during breeding or recovery periods |
| protected areas | provide places where fish can feed, breed and grow without capture |
| controlled net types and mesh size | reduce by-catch and allow small, immature fish to escape |
| quotas | limit the number or mass removed |
| monitoring | measures stock size and catch so controls can be adjusted |
A larger minimum mesh size lets small fish escape; reducing mesh size would catch more immature fish and undermine replacement.
Explain why conservation programmes matter
Conservation protects both species and the ecosystem functions and resources on which organisms and people depend.
| Reason | What is maintained |
|---|---|
| maintain or increase biodiversity | the number of species and their interactions |
| reduce extinction | populations and species that would otherwise be lost |
| protect vulnerable ecosystems | habitats that are easily damaged or slow to recover |
| maintain nutrient cycling | movement and reuse of mineral nutrients through ecosystems |
| maintain resource provision | supplies of food, drugs, fuel and useful genes |
Conservation is not only about saving one visible species. Protecting ecosystems can preserve many species, interactions and resources together.
Compare AI and IVF in captive breeding
Artificial insemination and in vitro fertilisation help selected captive animals reproduce without natural mating.
| Artificial insemination (AI) | In vitro fertilisation (IVF) |
|---|---|
| sperm is collected, checked or stored, then inserted into the female reproductive system at a fertile time | eggs and sperm are collected and fertilisation occurs outside the body |
| fertilisation occurs inside the female | embryos begin developing in culture before transfer to a female's uterus |
| semen from selected or distant males can be used | embryos can be selected, stored or transferred between breeding programmes |
Both methods can increase breeding opportunities and help managers choose parents from different populations to preserve genetic variation.
AI places sperm into the female; it does not create an embryo outside the body. IVF creates embryos outside the body before implantation.
Explain the genetic risks of a shrinking population
When population size decreases, fewer alleles remain and genetic variation is reduced.
A small population has fewer possible mates, so related individuals are more likely to breed. Inbreeding increases the chance that harmful recessive alleles are inherited together and expressed.
With less variation, fewer individuals may have features that help them survive a new disease, environmental change or other threat. Reproduction may also become difficult, so extinction risk rises further.
The required explanation is reduced genetic variation and its consequences; knowledge of genetic drift is not required.