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What is a population?
A group of individuals of the same species which makes up part of an ecosystem
The number of individuals present per unit area (or unit volume) of a habitat is calleed the...?
When birth rate is greater than death rate the population...?
When death rate is greater than birth rate the population...?
When a population colonises a new environment population numbers will increase until there are _____ ______ ?
What is the carrying capacity of a population?
The maximum population that the ecosystem can sustain
What are density-independent factors?
Factors which affect the size of a population regardless of the density of that population
Give an example of a density-independent factor
- Forest fire
- Excessive rainfall
- High / low temperatures
What are density-dependent factors?
Factors which only affect the population size once it has grown to a certain size and density
Give an example of a density-dependent factor
- Competition / shortage of food
- Toxic wastes
- Parasitism and disease
In a predator prey relationship prey numbers fluctuate over time. What happens to predator numbers?
They mirror they prey fluctuations but lag behind them
Describe what is happening at each labelled point in the graph
- A - increase in prey population perhaps due to increase in food supply
- B - resulting increase in predator population due to more prey
- C - decrease in prey population due to more predators
- D - decrease in predator population due to fewer prey
- E - increase in prey population due to fewer predators
_________ is the tendency of a population to decrease in size when it rises above a certain level and increase in size when it falls below that level?
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