Biology definitions

biosphere

The regions of the earth that encompasses all living organisms: plants, animals and bacteria.

Topography

the study of the physical features of an area, including its landforms, elevation, and the arrangement of biological and geological components.

Biomes

an area of the planet that can be classified according to the plants and animals that live in it.

Ecosystem

a geographic area where living and nonliving things interact

Ecology

the study of how living things interact with each other and their environment.

Biotic

living or once living components of a community

Abiotic

the physical and chemical non-living components of an environment.

Community

a group or association of populations of two or more different species occupying the same geographical area at the same time.

Environment

the place where organisms live or occupy

Habitat

the natural home or environment of a plant, animal, or other organism.

Population

a group of organisms of the same species that live in the same area and can reproduce with each other. 

Predators

organisms that hunt and kill other organisms for food. 

Parasites

an organism that lives on or in a host organism and gets its food from or at the expense of its host.

Terrestrial environments

land-based ecosystem, or community of organisms

Climate

the atmospheric weather of an area, measured and averaged over a long period of time

Biodiversity

the variety of life on Earth, including the different plants, animals, and microorganisms, as well as their genes and ecosystems.

Humus

dark, organic material that forms in soil when plant and animal matter decays

Limiting factor

anything that constrains a population's size and slows or stops it from growing.

Substrate

a supporting surface on which an organism such as a plant grows

Aquatic environments

the habitat for water-dependent living species including animals, plants, and microbes.

Photonic zone

the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis.

Dominant species

a species that is the most abundant or has the highest biomass in an ecosystem

binomial nomenclature

a two-part name system that identifies an organisms genus and species

Carl Linnaeus

zoologist that developed the binomial naming system for organisms

Classification keys

tools used by scientists to identify organisms that belong to species that have already been discovered.

dichotomous key

a tool used to identify organisms and objects based on their observable characteristics

competitive exclusion principle

the theory that no two species can occupy the same ecological niche for an extended period of time

Heterotroph (consumers)

An organism that cannot synthesise its own organic compounds from simple inorganic materials; it depends on other organisms for nutrients and energy requirements

Autotroph (producers)

organisms that are able to make their own food from raw materials and energy

Keystone species

a species of relatively low abundance that has a disproportionately large influence over lower trophic levels, determining the coexistence of these species in an area.

trophic level

the position an organism occupies in a food web

kingdom

1st tier (general → specific)

phylum

2nd tier (general → specific)

class

3rd tier (general → specific)

order

4th tier (general → specific)

family

5th tier (general → specific)

genus

6th tier (general → specific)

species

7th tier (general → specific)

food web

all of the food chains in a single ecosystem

food chain

a linear sequence of organisms through which nutrients and energy pass as one organism eats another

carnivore

an organism that eats mostly meat, or the flesh of animals

omnivore

an organism that eats plants and animals

herbivore

an organism that eats plants

decomposer

an organism that breaks down dead or decaying organisms and waste

niche

the match of a species to a specific environmental condition

species diversity

the number of species and abundance of each species that live in a particular location.

specialized niche

a very specific segment of ecospace occupied by a single species

niche generalist

organisms that have broad niches

edge effect

the change in population or community structure that happens at the boundary of two or more habitats.

phylogenetic trees

a diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor.