IB ESS Topic 2 - Ecosystems and Ecology

species

a group of organisms sharing common characteristics that interbreed and produce fertile offspring

population

a group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding

habitat

the environment in which a species normally lives

abiotic factors

non-living, physical factors that influence the organisms and ecosystem, e.g. temperature, sunlight, pH, salinity, pollutants.

biotic factors

the living components of an ecosystem - organisms, their interactions or their waste - that directly or indirectly affect another organism

niche

the particular set of abiotic and biotic conditions and resources to which an organism or population responds.

fundamental niche

the full range of conditions and resources in which a species could survive and reproduce

realised niche

the actual conditions and resources in which a species exists due to biotic interactions.

limiting factors

factors which slow down growth of a population as it reaches its carrying capacity

carrying capacity

the maximum number of a species or 'load' that can be sustainably supported by a given area

population dynamics

the study of the factors that cause changes to population sizes

competition

when two or more individual organisms try to exploit a resource that is in limited supply

predation

when one animal eats another animal

herbivory

when an animal eats a plant

parasitism

A symbiotic relationship where one organism (the parasite) lives in or on another (the host) feeding on or from it. One suffers, the other is harmed.

mutualism

a symbiotic relationship where both species benefit.

S and J population curves

generalised responses of populations to a particular set of conditions (biotic and abiotic factors)

community

a group of populations living and interacting with each other in a common habitat

ecosystem

a community and the physical environment it interacts with.

photosynthesis

the process by which green plants make their own food from water and carbon dioxide using energy from sunlight

food chain

the flow of energy from one organism to the next. It shows the feeding relationships between species in an ecosystem

trophic level

the position that an organism occupies in a food chain, or in a group of organisms in a community that occupy the same position in food chains

food web

a complex network of interrelated food chains

solar constant

the solar energy reaching the top of Earth's atmosphere (1400 J s-1 m-2 or 1400 watts per second)