What you need to know
- 4.16endemicDescribes a species found naturally in only one geographical area. and biodiversityThe variety of life in an area, including species richness and genetic diversity..
- 4.15Human activity threatening the variety of life.
- 4.21Evaluating conservationProtecting and managing species and habitats to maintain biodiversity. methods, including habitatThe place where an organism lives. as the missing context.
IUCN categories and island ranges are enrichment, not extra recall lists.
By the end, you should be able to…
- Apply endemism to an island ape.
- Link habitat conversion to populationAll the individuals of one species living in one area at the same time. and genetic loss.
- Evaluate captive care without treating it as a completed solution.
Build your understanding
Endemic to particular islands
Orang-utans are great apes of tropical forest. The Bornean orang-utan, Pongo pygmaeus, occurs naturally on Borneo and not on other continents; the Sumatran speciesA group of organisms that can interbreed to produce fertile offspring. is likewise restricted. That is endemicDescribes a species found naturally in only one geographical area. at island scale. Losing forest there cannot be offset by a healthy populationAll the individuals of one species living in one area at the same time. in Africa, because there is no such population.
IUCN currently lists the Bornean orang-utan as Critically Endangered. Treat that as a sourced conservationProtecting and managing species and habitats to maintain biodiversity. status, not as a specification definition. Status can be updated as new data are evaluated — the same community process you met in 4B.
The threat is the habitat
The main human pressures are conversion and degradation of lowland forest, including for agriculture, plus hunting and capture. When forest is fragmented, remaining groups are smaller and more isolated. gene flowMovement of alleles between populations when individuals migrate and interbreed. falls, which is 4C 5 in miniature: isolation inside one species, with inbreeding and lost alleleA different version of the same gene, found at the same locus. as 4C 4 would predict.
A high visitor count at a rescue centre does not restore canopy. nicheThe role of a species in its habitat: how it uses biotic and abiotic resources and interacts with other organisms. (4C 3) for an orang-utan includes large tracts of forest and a fruiting cycle. Captivity can keep individuals alive; it cannot supply that niche to a wild population.
Evaluate the conservation mix
in situDescribes conservation in the species’ natural habitat, such as a nature reserve. forest protection keeps the niche and allows ongoing selection. Rescue, veterinary care and some captive breeding can save individuals and support education (4.21). Reintroduction only makes biological sense if protected forest remains and if animals can forage. A zoo exhibit without land protection is education plus a small gene poolAll the alleles of all the genes in a population., not a wild species restored.
Use the same evaluation habits as 4C 6. Ask what happens to genetic diversityThe variety of alleles in a population or species., whether the original threat is removed, and whether claims of “saving orang-utans” mean wild, self-sustaining populations or surviving captives.
Make your reasoning visible
Start with endemism
Island range means local habitatThe place where an organism lives. loss is global extinction risk for that speciesA group of organisms that can interbreed to produce fertile offspring..
Keep 4.21 language
Research, breeding, reintroduction, education — each with a limit if forest still falls.
Avoid this misconception
The claim: If orang-utans live in zoos they are no longer endangered.
The correction: Red List status refers to wild populationAll the individuals of one species living in one area at the same time.. Captive animals do not replace a Critically Endangered wild species.
Check your understanding
Try each question before opening the suggested answer.
Practice question
Retrieval and explanation · suggested answer
Why is the Bornean orang-utan a useful example of endemism?
Show suggested answer
It occurs naturally on Borneo, so forest loss there cannot be offset by populations on other continents.
Practice question
Retrieval and explanation · suggested answer
How can habitat fragmentation reduce genetic diversity without every animal dying at once?
Show suggested answer
Isolated groups exchange fewer alleles, so inbreeding rises and alleles can be lost from small gene pools.
Practice question
Retrieval and explanation · suggested answer
Give one strength and one limit of captive care for orang-utans.
Show suggested answer
Strength: individuals can survive, be studied and support education. Limit: a small captive group cannot replace forest niche or a wild gene pool.
Take the idea further
Apply the same specification knowledge to an unfamiliar problem. Any extra assumptions are supplied in the question.
Stretch question
A campaign says “reintroduce all captive orang-utans next year”. Apply 4.21 to decide what must be true first, and what genetic issue remains.
Show a hint
Threat removal, skills, and founders.
Explore the reasoning
Protected habitat and low hunting must exist, and animals need skills to forage. Even then, if captives descend from few founders, the released gene pool may be narrow. Reintroduction without those conditions can waste animals and fail to restore a wild population.
Recall this lesson
Lesson recall questions
Question 1 of 5: What has happened to the variety of life over evolutionary time?
Variety of life under threat
Practice question
Retrieval and explanation · suggested answer
What has happened to the variety of life over evolutionary time?
Lesson: 4C 1: Biodiversity and Endemism
Try this from memory first.
Put your biology to work
Explore where these ideas appear in the world. Enrichment, not extra required recall.
Reading a status, not a slogan
4C · Thinking Bigger: Orang-utansThe IUCN Red List assessment for Pongo pygmaeus classifies the Bornean orang-utan as Critically Endangered, with habitat loss, degradation and hunting as central pressures. The assessment is a…Specification 4.15 · 4.21Read & use the scienceClose article
Why this matters
The IUCN Red List assessment for Pongo pygmaeus classifies the Bornean orang-utan as Critically Endangered, with habitat loss, degradation and hunting as central pressures. The assessment is a sourced judgement that can be amended. Use it to practise 4.15–4.16 and 4.21, not as an official exam figure to memorise. The Bornean orang-utan example connects endemism, habitat pressure and choices about conservation. A Red List category is a risk assessment, not a direct measurement of every genetic feature. Zoo breeding might protect some individuals, while forest protection addresses the habitat and food web. Comparing the two requires a clear outcome, such as surviving wild populations or retained genetic diversity. Students can practise reading an assessment critically without treating its latest numerical estimate as an exam fact.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 2, pp. 21–24. The application extends beyond required recall.
- 4.15 know that, over time, the variety of life has become extensive but is now being threatened by human activity
- 4.21 be able to evaluate the methods used by zoos and seed banks in the conservation of endangered species and their genetic diversity, including scientific research, captive breeding programmes, reintroduction programmes and education
Use the science
Why does a Critically Endangered listing not tell you the species’ heterozygosity index?
Explore a possible response
Red List criteria use decline, range and population size. H is a genetic sample statistic from 4.17; it needs genotypes, not only a threat category.
Explore the source
- IUCN Red List: Pongo pygmaeusIUCN Red List
An intergovernmental snapshot, not a mark scheme
4C · Biodiversity and EndemismThe 2019 IPBES Global Assessment concluded that nature is declining at rates unprecedented in human history, with human activity as the direct driver. It estimated that around one…Specification 4.15 · 4.16Read & use the scienceClose article
Why this matters
The 2019 IPBES Global Assessment concluded that nature is declining at rates unprecedented in human history, with human activity as the direct driver. It estimated that around one million animal and plant species are threatened with extinction. Those figures are a reviewed scientific synthesis. They are enrichment context for 4.15, not extra numbers you must recall as specification facts. Threatened species are not distributed evenly. Some are endemic to a limited region, so loss of that habitat can remove an entire lineage. Assessments combine many kinds of evidence and contain uncertainty; they are not a count made by visiting every organism. For the specification, define biodiversity and endemism clearly before discussing human pressures. The IPBES synthesis gives scale to the question, while a specific local survey would be needed to calculate richness or diversity in one habitat.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 2, pp. 21–24. The application extends beyond required recall.
- 4.15 know that, over time, the variety of life has become extensive but is now being threatened by human activity
- 4.16 understand what is meant by the terms biodiversity and endemism
Use the science
Why is “around one million species threatened” not the same statement as “one million species have already gone extinct this century”?
Explore a possible response
Threatened means at risk, using assessment criteria. Extinct means none remain. Mixing the two overstates what the evidence shows.
Explore the source
A backup of backups
4C · Conservation: Why and How?The Crop Trust describes the Svalbard Global Seed Vault as a backup of seed collections from genebanks around the world, held in permafrost as insurance against loss of…Specification 4.21Read & use the scienceClose article
Why this matters
The Crop Trust describes the Svalbard Global Seed Vault as a backup of seed collections from genebanks around the world, held in permafrost as insurance against loss of those collections. It is not a zoo, and it is not a wild habitat. It is one designed answer to the genetic-diversity half of 4.21, with the usual limit that frozen seed does not replace living ecosystems. Seed banks protect samples of genetic diversity, while zoos can coordinate breeding of living animals. Neither method is a substitute for protecting the conditions in which a species survives. The Svalbard backup illustrates why copies of seed collections are useful after accident or conflict, but viability, regeneration and access still require active management. In an evaluation, compare a method with the actual conservation goal: keeping alleles, restoring a wild population, or educating people. Each demands different evidence of success.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 2, pp. 21–24. The application extends beyond required recall.
- 4.21 be able to evaluate the methods used by zoos and seed banks in the conservation of endangered species and their genetic diversity, including scientific research, captive breeding programmes, reintroduction programmes and education
Use the science
Why does duplicating samples in Svalbard not by itself restore a vanished farmland variety to farmers?
Explore a possible response
Someone must still grow, select and share the seed under suitable conditions. The vault reduces the chance the last samples are lost.
Explore the source
- Crop Trust: Svalbard Global Seed VaultCrop Trust