3.5 Populations And Ecosystems Flashcards
(74 cards)
what is a density dependant factor
what is a density dependant factor
Density dependent factors that affect population size are things like competition, predation and disease. The effect of the factor on the population is bigger when the population is higher.
What are density dependent factors?
Density dependent factors are biotic factors that limit the size of a population.
What do density dependent factors determine?
Density dependent factors determine the carrying capacity of a population.
What is interspecific competition?
Interspecific competition is competition between different species.
What is intraspecific competition?
Intraspecific competition is competition between members of the same species.
what is density independant factor
A density independent factor affects populations whether they are large, small or just the same.
what are some density independant factors
These tend to be abiotic factors and tend to be sudden changes to the environment such as tsunamis, volcanic eruptions and wildfires.
define ecology
The study of living things and their interactions with each other and their environment.
define ecosystems
A characteristic community of interdependent species interacting with the abiotic components of their habitat.
define populations
All the members of one species in an area that can breed with each other.
all members of one species living with one another in a habitat at the same time.
define community
All the populations of different species living togteher in a habitat
define habitat
The place in an ecosystem where an organism lives.
define niche
The role of an organism in an ecosystem, generally a feeding role
define biotic and examples
All the living and organic components of an ecosystem
define abotic and give factors
All the non-living parts of an ecosystem
what happens during lag phase
Bacteria in a nutrient broth first go through a lag phase. They are synthesising enzymes and replicating DNA. The numbers of individuals rise slowly.
what happens during log phase
As food availability is high, the growth becomes exponential. Therefore, the cells divide rapidly, reproduction exceeds death rate and the population doubles for each unit of time. This is the log phase.
whats the stationary phase
As nutrients start to run out or get depleted,
the reproduction and deaths in the population stabilise,
this is the stationary phase.
Death and reproduction are equal.
whats the death phase
Eventually the toxins in the broth build up to such an extent that deaths exceed reproduction and the population decreases in the death phase. Death could also be caused by nutrients running out in the broth.
what are the advantages random sampling
every individual organism / species must have an equal chance of being included in the sample
the sampling method ensures that the sample is representative of the whole population of each species.
This reduces subjectivity and removes bias from the data collected
define species density
SPECIES DENSITY is the number of individuals of a given species in a given area. Calculated as mean number per quadrat converted to a mean number per m2 multiplied by the area of the habitat.
