Study

3.7.4 Populations in Ecosystems

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  • A method of estimating population size of motile organisms by marking a number of them, releasing them & then counting the number of marked organisms in a second sample
    Mark, release & recapture
  • all of the organisms of one species in an ecosystem
    Population
  • This describes how an organism fits into the environment. It describes what a species is like, where it occurs, how it behaves, its interactions with other species and how it responds to its environment.
    Niche
  • the non-living / physical part of an ecosystem that can affect population size
    Abiotic factors
  • a sampling area used for measuring the frequency or percentage cover of organisms (plants or slow moving organisms)
    Quadrat
  • the category of living factors in the environment of an organism that affect population size
    Biotic factors
  • Give two assumptions made when using the mark, release, recapture technique to estimate population size
    No immigration / migration (Ignore ref to emigration); No reproduction (Ignore ref to death); Idea of mixing; Marking does not influence behaviour
  • Conditions in the environment that limit population size - these can be biotic or abiotic factors.
    Limiting factors
  • The study of inter-relationships between organisms & their environment This environment includes living (biotic) factors (e.g. competition & predation) & non-living (abiotic) factors (e.g. temperature & rainfall).
    Ecology
  • The population size of a species that can be supported by the ecosystem
    Carrying capacity
  • When using a quadrat to estimate population size, we use a random number generator to avoid what?
    Bias
  • A group of similar organisms that can reproduce to produce FERTILE offspring
    Species
  • Two examples of biotic factors that affect the population size of an organism
    disease, predation, competition
  • Where one organism is consumed by another
    Predation
  • Differences between organisms of the same species
    Intraspecific variation
  • Competition between organisms of the SAME species e.g. for food or mates
    Intraspecific competition
  • All organisms of all populations in an ecosystem
    Community
  • competition between organisms of DIFFERENT species e.g. for food
    Interspecific competition
  • The range and variety of genes, species and habitats within a particular ecosystem
    Biodiversity
  • Give two examples of abiotic factors
    temperature, oxygen concentration, pH, light, carbon dioxide concentration
  • When using a quadrat to estimate population size, we take many samples to ensure that our data is what?
    Representative of the population
  • A self contained area including the biotic (living) community and abiotic (non-living) components interacting with one another
    Ecosystem
  • The place where an organism lives
    Habitat
  • A line along which organisms can be sampled in ecological studies. Particularly useful in ecosystems such as sea shores and sand dunes where abiotic conditions and species vary across the area being studied.
    Belt transect
  • The differences between organisms of different species.
    Interspecific variation