4.2 Flashcards
Define biodiversity.
Measure of variation found in the living world
Define habitat.
Where an organism lives
Define species.
a group of organisms that can freely interbreed to produce fertile offspring
How is random sampling carried out?
- sample sites inside habitat randomly selected
- random selection through computer generated co ordinates
Advantage of random sampling?
- Data is not bias
Disadvantages of random sampling?
- May not cover all areas
- Species with low presence may be missed leading to underestimate of biodiversity
How is opportunistic (non-random) sampling carried out?
- Sample decisions made using prior knowledge or during data collection
- May sample area where particular species can be seen
Advantages of opportunistic (non-random) sampling?
- Easier and quicker then random sampling.
Disadvantages of opportunistic (non-random) sampling?
- Bias -> colourful area
- Overestimate of biodiversity due to overestimate of importance
How is stratified sampling (non-random) carried out?
- Divide habitat in equal sized areas which appear different
- Sample separately
What are the advantages of stratified sampling (non-random)?
- All habitat samples
- Species not under represented
Disadvantage of stratified sampling?
- Possible over representation
How is systematic sampling carried out?
- Sample taken at intervals
- Line or belt transect used
Advantages of systematic sampling?
- Useful when clear gradient in habitat
Disadvantage of systematic sampling?
- Only species on line or within belt sampled leading to possible underestimation of biodiversity