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33 Cards in this Set
- Front
- Back
Ecosystem |
All the organisms living in a community plus all the non living (abiotic) conditions in the area in which they live |
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Community |
A group of interacting populations of different species living in the same place at the same time. |
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Population |
A group of organisms belonging to the same species found in the same area at the same time and potentially able to interbreed. |
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Habitat |
The environment of which an organism or population of organisms usually lives. |
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Abiotic |
The non living features of an ecosystem such as the temperature and the soil. |
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Biotic |
The living features of an ecosystem for example the presence of predators or food |
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Niche |
The role of a species within a habitat, for example what it eats when and where it feeds. |
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What happens if two species try to occupy the same Niche? What is this known as? |
A niche can only be occupied by one species. If they tried, they will be in competition. With one another. One will eventually be more successful until only one is left. Competitive conclusion |
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What is an Adaption? |
A feature that members of a species have that increases their chance of survival and reproduction. |
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What is Natural selection? |
Organisms with better adaptations are more likely to survive, reproduce and pass on advantages alleles. increases frequency of these alkenes in the population so adaptations become more common. |
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What is Population size? |
Total numbers of organisms of one species in a habitat |
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What is Carrying capacity? |
The maximum population size that can remain sustainable in an ecosystem |
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How do abiotic factors affect population size? Give examples |
Ideal= faster growth and reproduction Eg. Plant in higher temperatures ( less energy maintaining temp) Not ideal= slower growth and reproduction. Population size sometimes decreases. Eg. Mammals in cold conditions (more energy maintaining temp) |
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What is Interspecific Competition? And how does it link to the Competitive exclusion principle? |
Competition between different species. For same resources. Reduces pop size as less food. One will have competitive advantage, So one will increase and other decrease Which is CEP. |
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What is Intraspecific Competition? |
Competition between members of the same species. Fluctuation in pop size. Cycle: large pop, red food availability, smaller pop. Now more food available, pop starts to increase. Cycle repeats. |
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How does predation affect population size? |
Pop size of predators and prey is interlinked. As one changes=change in other. It creates a Selection pressure meaning members of species better adapted at evading predators more likely survive and reproduce . Each new species better adapted for survival. |
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Investigating bacteria population. What does low absorbance of light mean? |
There aren't many bacteria present. High absorbancd of light shows lots of bacteria present. |
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How many ways can you measure abundance of a population? |
Frequency and Percentage cover |
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What is abundance? |
Number of individuals of one species in a particular area. Frequency - number of samples recorded % cover- how much area is covered by species |
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What is distribution? |
How a species is spread across a habitat. Clumped - favour specific areas Even Random |
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How to carry out random sampling? |
1. Choose an area 2. Split into grid. Random coordinate generator 3. take as many samples as possible (MIN 15) 4. Carry out statistical tests |
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Why randomly sample? |
Prevent any bias, the larger the more reliable |
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What methods can you use to investigate population sizes? |
Quadrat Transect |
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What is a quadrat? |
A square frame divided into smaller squares. It's placed at random in the investigated area. |
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What is Species Frequency? |
The likelihood of a particular species occuring withing the quadrat. Eg 15/30 squares. Frequency is 50% |
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What is percentage cover? |
Count number of squares that's covered by species. (More than half covered is one square) calculate percentage. |
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What are transects? |
Lines through study area. Samples taken along it. Useful if change in abiotic factors across area (eg shade to light). Shows DISTRIBUTION |
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Two types of transects |
Belt transects and interrupted belt transects |
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What is a belt transect? |
Quadrats next to each other in a line. |
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What is interrupted belt transect? |
Quadrats at regular intervals |
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What is the mark release recapture method? |
Harmless marking after capture. Released to environment. Allow mixing with population. Recapture and count how many marked. |
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What is mark release recapture equation? |
Total pop size = No. 1st sample X no. 2nd sample DIVIDED BY No. marked in 2nd sample |
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Comment on the accuracy of the mark release recapture method. |
Depends on a few assumptions: Marked sample has time to mix with non marked Marking doesn't affect survival Mark is still visible No change in population size die to births deaths or migration Stress can lead to reduction in survival. |