Evaluating zoos and seed banks in conservationSpec 4.21
In short
Zoos conserve endangered animals through captive breeding programmes, reintroduction programmes, scientific research and education. Seed banks store seeds as a low-cost way of conserving plant species and their genetic diversity. Each approach has strengths and limitations, which must be weighed up to evaluate how effective it is.
Zoos
- Captive breeding programmes: animals are bred under controlled conditions. Studbooks record pedigrees and animals are exchanged between zoos so mating partners are unrelated, to maintain genetic diversity and avoid inbreeding.
- Reintroduction programmes: animals bred in captivity are released into protected habitat, increasing wild populations.
- Scientific research: study of the biology, behaviour and breeding of species, and techniques such as artificial insemination and embryo storage, help conservation in the wild.
- Education: visitors learn about threatened species, which increases support and funding.
Seed banks
Seed banks store seeds from many species, dried to a low water content and kept at low temperature (for example −20 °C), which slows metabolism and keeps seeds viable for many years. Seeds can later be germinated to grow new plants or to reintroduce a species.
- Seeds are collected from many plants across a species' range, to capture as much of its genetic diversity as possible.
- Scientific research: seed banks study the best conditions for drying, storing and germinating each species, and regularly test samples for viability by germinating them.
- Reintroduction: plants grown from stored seeds can be used to restore populations in protected or restored habitats.
- Education: seed banks and botanic gardens explain the value of plant diversity, for example as a source of food crops and medicines.
| Strengths | Limitations | |
|---|---|---|
| Zoos | Protect animals from threats such as hunting and habitat loss; managed breeding maintains genetic diversity; research and education; reintroduction can restore wild populations | Expensive and space-limited, so only a few individuals of a few species; small populations may lose genetic diversity; animals may lose natural behaviours and not survive reintroduction; habitat must still be protected for release; risk of disease |
| Seed banks | Cheap, take little space and store many individuals of many species; protect against loss in the wild; store a wide range of alleles for future use; seeds can be tested for viability and regrown | Some seeds cannot be dried or frozen; seeds may lose viability, so need testing and regrowing; plants in storage do not adapt to changing conditions; seeds from small samples may carry limited genetic diversity; a reintroduction needs suitable habitat |
In evaluate questions give a balanced judgement: weigh strengths against limitations and end with a reasoned conclusion, for example that both are useful but only if natural habitats are also protected.
(opens full size in a new tab)Quick check
Define niche.
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The role of a species within its habitat, including how it obtains resources and its interactions with other species.
Name the three types of adaptation.
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Behavioural, anatomical and physiological.
In the Hardy-Weinberg equation, what does 2pq represent?
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The frequency of the heterozygous genotype.
Name two causes of changes in allele frequency.
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Mutation and natural selection.
Why are seeds dried before storage in a seed bank?
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To reduce water content, which slows metabolism and prevents germination and damage from ice crystals.
Written and checked against the Edexcel International AS Level Biology (XBI11) specification · Updated October 2026