Edexcel A SNAB Topic 4
- Created by: izziewarrington
- Created on: 05-03-18 09:33
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- Topic 4
- Definitions
- Species - A group of organisms with similar physiology and behaviour, who can interbreed and produce fertile offspring. They are reproductively isolated.
- Habitat - where organisms live. Each habitat has a set of conditions which supports distinctive organisms.
- Population - a group of interbreeding individuals of the same species found in an area.
- Community - the various populations within one area.
- Niche - the way an organism exploits its environment.
- Adaptations
- Behavioural - actions by organisms that help them to survive or reproduce.
- Physiological - features of the internal makeup of an organism which help them to survive or reproduce.
- Anatomical - structures that can be seen when an organism is dissected.
- Natural Selection
- 1. A few organisms within a population have naturally-occuring genetic variation with new alleles created through mutations.
- 2. A change in the environment causes a change in the selection pressures acting on the population.
- 3. An allele that had no previous advantage is now favourable.
- 4. Organisms with that allele are more likely to survive and reproduce.
- 5. Their offspring are more likely to have the allele, so it becomes more common in the population.
- This changes: - the size of the gene pool
- 5. Their offspring are more likely to have the allele, so it becomes more common in the population.
- 4. Organisms with that allele are more likely to survive and reproduce.
- 3. An allele that had no previous advantage is now favourable.
- 2. A change in the environment causes a change in the selection pressures acting on the population.
- 1. A few organisms within a population have naturally-occuring genetic variation with new alleles created through mutations.
- Biodiversity
- Refers to the diversity within a species.
- Species Richness - the number of species present in a given habitat.
- A highly diverse community will have high species richness and high species evenness.
- A hotspot is an area with particularly high diversity.
- Taxonomy
- Kingdom Phylum Class Order Family Genus Species
- Endemic Species
- A species which is geographical isolated and can only be found in one area.
- These species are often endangered.
- Definitions
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