3.7.4 Populations in ecosystems Flashcards
define community
all living organisms of all species found in a given area/habitat/ecosystem at a given time
define ecosysytem
self contained area including all the living (all the communities within it) and non living factors interacting with one another
define niche
describes how an organism fits into the environment/its role in the ecosystem - no organism can occupy the same niche
define succession
used to describe changes that occur over time, in the species that occupy a particular area
define abiotic
non living factor in the environment of an organism e.g temperature, oxygen concentration, pH, light
define biotic
the living factors in the environment of an organism e.g. disease, predation, competetion
define population
all of the organisms of one particular species in a given habitat/area at the same time
What conditions are necessary in order for the mark release recapture investigations to be valid? what assumptions are made?
- markings dont make organism visible to predators
- markings dont harm the organism
- No migration/immigration
- sample large
- no reproduction
- no births or deaths
- markings are nor easily rubbed off/worn off
- marked individuals in 1st sample distribute themselves evenly back into the population
Name two types of competition
interspecific and intraspecific
Define intraspecific competition
competition between organisms of the SAME species
Define interspecific competition
competition between organisms of DIFFERENT species
What is a pioneer species?
the first organism to colonise in the first stage of succession - it can with stand hostile environments
define a climax community
A stable community/no further succession.
All the organisms that make up the final stage of succession - animals and plants
define a habitat
place where a habitat where an organism lives
define carrying capacity
The population size of a species that an be supported by the ecosystem
within an ecosystem which 2 major processes occur
- flow of energy through the system
2. recycling of nutrients within the system
define population size
the number of individuals in the population
what do we call factors that limit the size of the population
limiting factors - they can be abiotic or biotic
Give examples of abiotic factors that limit the size of a population
light, temperature, pH, water, humidity
give examples of biotic factors that limit population size
availability of food, predation, disease
The growth and size of the human population depends on
birth rate v death rate - its the balance between these two that determines if if increases, decreases or remains the same (also includes immigration and migration)
define immigration
when people move into a population from outside
define emmigration
when people move out of a population and leave
In a stable population what can be said about birth and death rates?
they are equal
In an increasing population what can be said about birth and death rates?
birth rates are higher than death rates
define predation
where one organism is consumed by another
Define prey
An organism that is consumed/hunted by another organism
Define a predator
An organism that hunts and feed on other organisms