Biology: Topic 4 - Community Level Systems

Decomposers

an organism that breaks down carbon in dead animals and plants

Carbon cycle

a natural cycle through which carbon moves by respiration, photosynthesis and combustion, in the form of carbon dioxide

Aerobic compost

dead and decaying plant material formed in the presence of oxygen.

Anaerobic compost

dead and decaying plant material form in the absence of oxygen.

Ecosystem

the interaction of a community of living organisms with the non-living parts of their surroundings

Biodiversity

range of all the different species living in an ecosystem, including plants, animals, fungi and protoctista.

Population

the total number of one species in an ecosystem

Habitat

the place where an organism lives in an ecosystem; e.g. the worm’s habitat is the soil

Interdependence

where organisms depend on each other for survival e.g. plants need animals for carbon dioxide and seed dispersal; animals need plants for food and oxygen; i.e. they depend on each other for survival

Abiotic factor

physical or non-living conditions that affect the distribution of a population in an ecosystem, such as

Biotic factor

factors caused by living organisms, such as- food availability and competition between species

Distribution

how living organisms are dispersed/spread out over an ecosystem

Competition

when different species in an ecosystem compete for the same resources

Intraspecific competition

competition among organisms from the same species

Interspecific competition

competition between two different species of organism

Consumer

trophic level of heterotroph organisms

Producer

organisms in a food chain that make food using sunlight

Mutualism

when two organisms live together and they both benefit from the relationship

Predator

animal (consumer) that kills and eats other animals

Parasitism

a relationship between two organisms where one benefits and the other is harmed, e.g. tapeworms in humans

Apex predator

predator on top of the food chain, not eaten by any other predator.

Biomass

the dry mass of organisms

Decomposer

an organism that breaks down carbon in dead animals and plants

Pyramid of biomass

table of dry weight of organisms at different trophic levels in an ecosystem, which forms a pyramid shape

Trophic level

feeding positions in a food chain

Egestion

the process by which undigested plant material leaves the body of an organism in faeces

Biomass

the dry mass of organisms

Efficiency

the proportion of biomass transferred between trophic levels.

Directly proportional

describes a relationship between two variables on a graph where the line of best fit goes through 0,0.

Gradient

the steepness or slope of a line plotted on a graph

Intercept

the point where two lines meet, often used in graphs to determine when a line crosses the y axis (y intercept)

Linear

a straight line on a graph that indicates a strong relationship between the two plotted variables

Rate

the speed at which an event is occurring over time; can be calculated using the gradient on a graph.