Populations

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What is interspecific competition?
Competition between 2 DIFFERENT species
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What is intraspecific competition?
Competition between 2 organisms of the SAME species
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Name examples of abiotic factors which limit a population
Temperature, Light intensity, Nutrient availability, pH, water and humidity
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How do you work out estimated population size?
Total number of individuals in 1st sample x total number of individuals in 2nd sample/ number of marked individuals recaptured
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What does random sampling avoid?
Bias making data more reliable and valid
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Why is a large sample better than a smaller one?
It reduces the effects on chance on the investigation, it also gives enough results to make a average and do statistical tests.
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What is a ecosystem?
All the interrelated organisms and their physical environment both biotic and abiotic
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What are the two major processes within a ecosystem?
The flow of energy through the system, the cycling of elements in the system
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What is a population?
All organisms of one species living in a habitat at one time
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What is a community?
All populations of all species living in a particular habitat or ecosystem
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What is a habitat?
The part of ecosystem where a particular organism lives. There are many habitats in a ecosystem
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What is a niche?
The role of a organism in its habitat/ecosystem. How it effects other organisms (what it eats and who it is eaten by) It is biotic and abiotic interactions
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What is a fundamental niche?
It is larger than the realised niche. It is were a species can live rather than were it does live. It is ignoring predation and resource limitation
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Why can't two species occupy the same niche?
Because on species will out compete the other for resources, the competitive exclusion principle will occur.
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What is the competitive exclusion principle?
This is competition between two species which may of initially occupied the same niche, one species eventually out competes the other and the other population size diminshes
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What is predation?
When one animal is consumed by another
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How does predation effect population size of prey?
Predators eat their prey, this reduces the preys population size, A reduced population size, mean less food for the predator, this results in more intraspecific competition for food so the predators population size decreases. Less predation = + prey
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How does predation effect population size of predator?
More prey in a population means less competition so predator population increases, but this means more prey is eaten and this population decreases causing more competition and predator population to decrease
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What is selection pressure?
This is where only individuals who are well adapted to survive predation, live on.
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What two things have lead to a explosion in human population?
Industrial revolution and development of agriculture
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What is immigration?
Where individuals join a population from the outside
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What is emmigration?
Where individuals leave the population
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What is the equation for population growth?
Population growth = (births + immigration) - (death + emmigration)
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How do you work out percentage population growth?
Population change during period/population at start of period x 100
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What is birth rate?
Number of live births each year for every 1000 people
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What is death rate?
Number of death each year for every 1000 people
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Name 4 factors increasing birth rate
Lack of contraception, children go to work, lack of education and social pressures.
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Name 4 factors decreasing death rate
Better medical facilities, No wars, Better sewage, More care homes, clean water etc.
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How do you calculate birth rate?
Number of births that year/ population that year x 100
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How do you calculate death rate?
Number of deaths that year/population at start of the year x 100
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What are the characteristics of a LEDC population pyramid?
Wide base, not very high and triangular
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Other cards in this set

Card 2

Front

What is intraspecific competition?

Back

Competition between 2 organisms of the SAME species

Card 3

Front

Name examples of abiotic factors which limit a population

Back

Preview of the front of card 3

Card 4

Front

How do you work out estimated population size?

Back

Preview of the front of card 4

Card 5

Front

What does random sampling avoid?

Back

Preview of the front of card 5
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