3.7.3 Populations and Ecosystems Flashcards
Why is it important to measure species diversity?
to compare different habitats or study how a habitat has changed over time
Define niche
The role of a species in it’s environment
Define community
All of the organisms of different species that live in the same habitat and interact with each other
Define population
All the organisms of one species in a habitat
Define mutualism
A relationship between two organisms where both benefit
Define ‘population size’
The number of individuals of one species in a particular area
Define ecosystem
All the organisms living in a particular area and all the non living (abiotic) factors
Define habitat
The place where an organism lives
Define species distribution
Where a species is within a particular area
Define abundance
The number of individuals of one species in a particular area
Define biotic factors
The living features of the ecosystem (e.g. predators, prey, microorganisms)
Define abiotic factors
The non living features of the ecosystem
Define carrying capacity
The maximum stable population size of a species
What happens as a population of organisms approaches carrying capacity (k strategist)
Density dependent factors limit the rate of population growth (eg availability of food). This is sometimes referred to as environmental resistance
How can some organism have a polulation above carrying capacity
They reproduce very quickly (often small organisms - R strategists) and a population boom will be followed by a bust (dramatic decrease).
what formula determines the size of a bacterial population growing exponentially
Population = Starter population x 2^n (where n = number of generations)
why do we often use logarithmic graphs when plotting bacterial populations
When the populations have a very large range (ie you have to plot very small numbers and very large numbers)
What is a producer (or an autotroph)?
Organisms that produce their own food (usually through photosynthesis)
Which factors determine the numbers and distribution of organisms in a habitat ?
Biotic and Abiotic factors
What is primary succession?
Occurs on land that has been newly formed or exposed
What is secondary succession?
Occurs on land that has been cleared of all plants, but where the soil remains
What is a climax community?
A stable community usually dominated by trees that remains unchanged unless conditions in the habitat change
What is a pioneer species?
The first species to colonise an area, tends to be very specialised