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Summary Biology Unit 4 AQA ALEVEL New Spec Full Revision Notes
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Full A-Level Unit 4 Biology Revision Notes; Genetic information, variation and relationships between organisms.
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Section 4: Genetic information,variation and relationships
between organisms
What is Biodiversity?
Variety of habitats and species in an ecosystem.
What is Species Diversity?
- Number of diferent species.
- Number of individuals for each species.
What is Genetic Diversity?
Variety of alleles in a species populatonn (the larger number of individuals in a
species, the larger the genetc diversitt).
Benefit of hihh species diversity?
- Stable ecosystem
- Each species is less likely to become extnct (due to high genetc
diversitt).
- If a species does become extnct it will not afect the food chain as there
are other species available.
How to measure Species Diversity for an area?
Species Diversity Index: takes into account the number of diferent species and
how many individuals there are for each species. The larger the species
diversity indexn the larger the species diversity.
How does deforestation lower species diversity?
- (Deforestaton is the removal of trees for wood & space).
- Decreases plant and animal species diversity.
- Less variety of habitats and food sources.
How does ahriculture/farminh lower species diversity?
- Deforestaton to make space for farm.
- Only grow a few plants & keep a few animal species.
- Selectvely breed plants & animals.
- Use pestcides to kill other species.
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