IB ESS Topic 2 Vocabulary

Abiotic Factor

A non-living, physical factor that may influence an organism or ecosystem

Biotic factor

A living biological factor that may influence an organism or ecosystem

Biosphere

The part of the Earth inhibited by organisms

Biome

A collection of ecosystems that share similar climates

Biomass

The mass of organic material in organisms or ecosystems, usually per area

Niche

A set of biotic and abiotic conditions and resources that an organism or population depends on

Habitat

The environment in which a species usually lives

Population

A group of the same species, living in the same area at the same time, interacting and breeding.

Species

A group of organisms that are capable of breeding and producing fertile offspring. Share similar characteristics and genetic makeup.

Trophic Level

The place an organism occupies on a food chain

Interspecific Competition

The struggle between two organisms of different species for the same (biotic or abiotic) resource.

Intraspecific Competition

The struggle between two organisms of the same species for the same (biotic or abiotic) resource.

Predation

A relationship between two organisms in which one hunts, kills, and eats the other one.

Herbivory

A form of competition in which an organism eats producers such as plants, algae, and photosynthesising bacteria

Ecological Niche

The role of a species in an ecosystem

Ecosystem

Organisms’ interactions with biotic and abiotic factors. A community of living organisms in a particular area.

Community

Populations of different species interacting in a shared environment.

Individual

One living organism of a species

Parasite

Lives on or in living hosts and gets their food from the host, at the host’s detriment.

Parasitism

Where one species lives off another gaining most of its food.

Mutualism

Symbiotic relationship in which both species benefit

Symbiotic Relationship

A close, prolonged association between two or more different species

Herbivore

Plant eating organism

Carnivore

Animal eating organism

Omnivore

Organism which eats both animals and plants

Detritivore

Organism that feeds on decomposing organic matter. Eats dead plant/animal material.

Decomposer

Organism which breaks down dead materials to recycle nutrients.

Scavenger

Organism which eats mostly decaying biomass, usually carnivores

Saprotroph

Organisms that live on dead or decaying organisms

Carrying Capacity

The maximum number of species that can be sustainably supported by a given area

Limiting factors

Slow down the growth of a population as it reaches its carrying capacity

Density dependant limiting factors

Mostly biotic, cause a change in population with a higher density

Density independent limiting factor

Mostly abiotic, change the size of a population regardless of density

Inorganic (substance)

Compounds which do not contain carbon (with the exception of carbon dioxide and carbonates) and are not derived from living matter.

Denitrification

The conversion of nitrates to nitrogen gas in the atmosphere by bacteria

Nitrification

The conversion of ammonia to nitrates by bacteria.

Nitrogen fixation

The conversion of atmospheric nitrogen to ammonia by bacteria and/or lightning.

Haber process (HL)

industrial process that produces ammonia from nitrogen and hydrogen for use as fertilizer

Carbon sequestration

The process of capturing and storing atmospheric carbon dioxide.

Residence time

the average period that a carbon atom remains in a store

Fossil fuels

stores of carbon with unlimited residence times

Organic (substance)

Carbon-containing molecules associated with living organisms, for example, carbohydrates, lipids, nucleic acids, proteins, and hydrocarbon fuels.

Food webs

Two or more food chains linked together and can show that a single species can occupy multiple trophic levels.

Gross primary productivity (GPP)

The total gain in energy or biomass per unit area per unit time fixed by photosynthesis in green plants.

Gross secondary productivity (GSP)

The total gain by consumers in energy or biomass per unit area per unit time through absorption.

Net primary productivity (NPP)

The gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R). This is potentially available to consumers in an ecosystem.

Net secondary productivity (NSP)

The gain by consumers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R).

Dry mass

is approximately equal to mass of organic matter (biomass) since water represents the majority of inorganic matter in most organisms

Ecological pyramids

Quantitative models showing changes between organisms at different trophic levels in a food chain. They include pyramids of numbers, biomass, and productivity.

Bioaccumulation

The build-up of persistent or non-biodegradable pollutants within an organism or trophic level because they cannot be broken down.

Biodegradable

When something is capable of being broken down by natural biological processes; for example, the activities of decomposer organisms.

Biomagnification

The increase in concentration of persistent or non-biodegradable pollutants along a food chain due to the decrease of biomass and energy.

Polychlorinated biphenyl (PCB)

Chemicals that affect innate immune functions in humans.

First law of thermodynamics

The principle of conservation of energy, which states that energy can be transformed but cannot be created or destroyed.

Heterotrophs

Organisms that obtain their organic nutrients from other organisms.

Chemoautotrophs

Organisms that use chemical oxidative processes to synthesize organic nutrients from inorganic sources.

Photoautotroph

Organisms which use sunlight to synthesize organic nutrients from inorganic sources.

Primary productivity

The gain by producers in energy or biomass per unit area per unit time. This term could refer to either gross or net primary productivity.

Secondary productivity

The biomass gained by consumers, through feeding and absorption, measured in units of mass or energy per unit area per unit time.

Ecological efficiency

the percentage of energy received by one trophic level that is passed on to the next leve

Autotrophs

Organisms that make their organic nutrients from inorganic sources.

Second law of thermodynamics

This law states that the quality of energy changes as it is transferred or transformed, from useful energy (for example, solar radiation) to low-quality energy (e.g., heat).

Consumers

Organisms that ingest live or recently dead organisms, and are further classified as herbivore, carnivore, or omnivores.