Populations and ecosystems
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Define ecology
study of inter-relationships between organisms and their environment
Define the term abiotic factor
Non living factors in an environment eg temperature or rainfall
Define the term biotic factor
living factors in an environment eg competition and predation
Define ecosystem
dynamic system made up of a community and all of the non living factors of its environment
Name two major process that occur within an ecosystem
flow of energy cycling of elements
Define population
group of individuals of the same species occupying the same habitat at the same time and can interbreed
Define community
the populations of different species in a particular place at the same time
Define habitat
the place where an organism normally lives
Define microhabitat
a smaller unit within a habitat with its own microclimate
Define niche
how an organism fits into its environment (where the organism lives and what it does there)
Why do we describe populations as dynamic?
they vary in size and composition over time
Why is it necessary to use a logarithmic scale to plot growth curves for rapidly reproducing organisms?
So that all of the data can be represented on the same axis
Define limiting factor
factor that limits the growth of a population
State the factors that affect the size of a population
abiotic and biotic factors affect rate of growth and size of a population
Define carrying capacity
the size of population of a species that can be supported by the ecosystem
Describe how temperature affects a population size
different species have different optimum temperatures. Temperatures above or below these may slow/denature enzymes in cold blooded animals or require excessive energy use to maintain in warm blooded animals
Describe how light affects population size
Light is required for photosynthesis. More light, more photosynthesis, more biomass both for plant survival and for animals to feed on
Describe how pH affects population size
pH affects action of enzymes. Organisms have an optimum pH and will not survive well in pH away from optimum
Describe how water affects population size
In scarce water conditions only well adapted organisms survive.
Describe how humidity affects population size
in low humidity transpiration and water loss increase. Plants and animals well adapted to tolerate low humidity will have larger population size
Why is it necessary to use a logarithmic scale to plot growth curves for rapidly reproducing organisms?
So that all of the data can be represented on the same axis
Describe competition
when 2 or more species share a resource that is insufficient to satisfy their requirements fully
Describe intraspecific competition
competition between members of the same species
Describe interspecific competition
competition between individuals of different species