Share OCR A A Level biology Yr 12
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What are the three levels of biodiversity?
Habitat, species and genetic
What is species richness?
The number of different species in an area
What is species evenness?
How even the number of individuals between species in an area are
What is random sampling?
Selecting samples without a pattern or bias
What is systematic sampling?
Sampling at regular intervals or locations, perhaps using a transect
Name 2 pieces of equipment used for sampling insects.
Pitfall trap, sweep-net or pooter
What apparatus is used for sampling plants?
Quadrat
What is the mark-recapture method used for?
Estimating population size of mobile animals
What can cause errors in mark-recapture?
Death, immigration, emigration, or marks falling off
Name 3 major threats to biodiversity.
Habitat destruction, pollution, invasive species, over-exploitation of resources etc
What impact do invasive species have on biodiversity?
They compete with native species and may cause extinction
What is habitat fragmentation?
Breaking habitats into smaller, isolated patches making interbreeding more difficult, leading to a decrease in genetic biodiversity
Why is biodiversity important for ecosystems?
It increases ecosystem stability and resilience
How does biodiversity benefit humans?
Provides food, medicine, and ecosystem services
What is Simpson’s Diversity Index used for?
Measuring species biodiversity by taking into account species richness and evenness
What does a high Simpson’s Diversity Index indicate?
High biodiversity with many species evenly distributed
