Ecosystems Flashcards
Define ecology.
The study of relationships between organisms, or groups of organisms, and their environments.
Define habitat.
The place where an organism lives (the natural environment of an organism).
Define population.
A group of organisms of the same species, in the same place (at the same time) that can interbreed.
Define community.
All of the organisms of different species (living within the same area) that interact together.
Define competition.
The result of a demand, by two or more organisms, on a limited supply of resources (e.g. food, mates, light etc). Can be intraspecific (within the same species) or interspecific (between different species).
Define ecological niche.
The role that an animal or plant species plays in the environment and the status of an organism within its environment (which affects its survival). Often defined in animals by feeding habits & size.
Define competitive exclusion principle.
No two ecological niches can be exactly the same (i.e. niches are exclusive and mutual coexistence of two species will require their niches to be sufficiently different). In competitive exclusion one species is eliminated by another in an area via interspecific competition.
What is an ecosystem?
‐ A community of organisms ; ‐ Interacting with one another, plus the environment in which they live and with which they interact ; (i.e. interaction of biotic and abiotic components )
‐ These biotic and abiotic components are linked together through nutrient cycles and energy flows ; ‐ Ecosystems are described as dynamic, meaning that the interactions within them can change due to interference / disturbance ;
-The tendency of a system to remain close to its equilibrium state, despite disturbance, is termed its resistance. On the other hand, the speed with which it returns to its initial state after disturbance is called its resilience.
What is a biotic factor?
A factor created by a living organism which affects the life of another organism.
For example:
‐ A predator consuming its prey ‐ Parasitism
‐ Mutualism ‐ two organisms of different species live in close association and benefit from relationship
‐ Interspecific competition (between species)
‐ Intraspecific competition (within species)
What is an abiotic factor?
A non‐living, chemical or physical component in the environment. For example: ‐ Light intensity ‐ Water supply ‐ Humidity ‐ Wind speed ‐ Temperature ‐ Oxygen and carbon dioxide concentration ‐ pH of water and soil ‐ Availability of inorganic ions ‐ Forest fire
Define food web.
Interacting chains of organisms, existing in any natural community, through which energy and matter are transferred. Each stage in a chain feeds on, and thus gains energy from, the one preceding it (and is in turn eaten by the one succeeding it). All food chains start with autotrophic organisms.
Define trophic level.
The position of an organism in a food web (n.b. organisms may occupy more than one feeding level). The number of trophic levels in a community is limited by the inefficiency of energy flow from one level to the next.
Define producer / autotroph.
An organism that synthesises complex organic molecules (such as carbohydrates, fats, and proteins) from simple inorganic molecules using energy from light (photosynthesis / photoautotroph) or inorganic chemical reactions (chemosynthesis / chemoautotroph).
Define consumer / heterotroph.
An organism that obtains food by feeding on other organisms or organic matter (due to lack of the ability to manufacture own food from inorganic sources). They produce complex organic molecules from organic sources of carbon e.g. plant or animal matter. All animals, protozoans, fungi, and most bacteria are heterotrophs.
Define detritivores.
Organisms feeding on dead organic material, especially plant detritus. (e.g. earthworms & woodlice).
