DAT Biology Ecology

ecology

the study of the interactions between organisms and their environment

abiotic

the physical or nonliving component of an organism's environment

biotic

the living component of an organism's environment

species

any group of similar organisms that are capable of producing fertile offspring

population

a group of organisms of the same species living together in the same location

community

consists of populations of different plants and animal species interacting with each other in a given environment

biotic community

community that includes only the population and not their physical environment

ecosystem

includes the community and the environment

biosphere

all portions of the planet that support life

lithosphere

the rigid outer part of the earth, consisting of the crust and upper mantle.

atmosphere

A mixture of gases that surrounds a planet or moon.

hydrosphere

All the water at and near the surface of the earth, 97% of which is in oceans

photic zone

the top layer of water through which light can penetrate; where all photosynthetic activity takes place

aphotic zone

Portion of the marine biome that is too deep for sunlight to penetrate; only animal life and other heterotrophic life exist

texture

the quality of soil that determines its water-holding capacity

loams

Soils containing a mixture of clay, sand, silt, and humus. Good for growing most crops.

acidity

the quality of soil that determines what types of plants grow in which types of soil

nitrates

Nitrogen-based nutrients commonly found in fertilizers and pesticides

phosphates

Phosphorous-based nutrients commonly found in fertilizers and pesticides.

minerals

affect the type of vegetation that can be supported

humus

material formed from decaying plant and animal life in the soil

niche

the functional role of an organism in its ecosystem; embodies every aspect of an organism's existence

habitat

the physical place where an organism lives

autotrophs

organisms that manufacture their own food

heterotrophs

organisms that cannot synthesize their own food and must depend upon autotrophs or other heterotrophs in the ecosystem to obtain food and energy

herbivores

animals that consume only plants or plant foods

symbiotic bacteria

inhabit the digestive tracts of herbivores and allow the breakdown and utilization of cellulose

omnivores

animals that eat both plants and animals

carnivores

animals that eat only other animals

symbiosis

living together in an intimate, often permanent association, which may or may not be beneficial to both participants

obligatory

type of symbiosis in which one or both organisms cannot survive without the other

commensalism (+/0)

a symbiotic relationship in which one organism is benefited by the association and the other is not affected; the host neither discourages nor fosters the relationship

mutualism (+/+)

a symbiotic relationship from which both organisms derive some benefit

parasitism (+/-)

a symbiotic relationship in which one organism benefits at the expense of the host

ectoparasites

parasites on the exterior surface of the host

endoparasites

parasites that live within the host

chemosynthetic

energy producing

saprophytic

bacteria of decay

predators

free-living organisms that feed on other living organisms; includes carnivores AND herbivores

saprophytes

protists and fungi that decompose dead organism matter externally and absorb nutrients

scavengers

animals that consume dead animals

osmoregulation

regulation of solute concentrations and water balance by a cell or organism

poikilothermic

cold-blooded; an animal whose body temperature varies with that of the surrounding environment.

homeothermic

warm-blooded; able to maintain a constant body temperature

food chain

A series of steps in which organisms transfer energy by eating and being eaten

autotrophic green plants, chemosynthetic bacteria

the 2 producers in the food chain

primary consumers

in the food chain, animals that consume green plants; herbivores

secondary consumers

in the food chain, animals that consume the primary consumers; carnivores

tertiary consumers

in the food chain, animals that feed on secondary consumers; also carnivores

food web

an intricate collection of interconnected food chains

pyramid of energy

visual representation that shows that each consumer receives less energy from the consumer before them

pyramid of mass

visual representation that shows how each consumer level on the food chain can support less biomass due to a loss of energy

pyramid of numbers

visual representation that shows that at each level in the food chain, there are fewer of a consumer

decay, nitrifying, denitrifying, nitrogen fixing

four kinds of bacteria involved in the nitrogen cycle

nitrifying bacteria

bacteria that convert ammonia (NH₃) into nitrites and then nitrates so that plants can use them

denitrifying bacteria

bacteria that break down nitrogenous compounds into free nitrogen, which enters the atmosphere (NO₃⁻ →N₂)

nitrogen-fixing bacteria

bacteria that remove nitrogen gas from the air and convert it to ammonia

ecological succession

the orderly process by which one biotic community replaces another until a climax community is established

sere

each community stage in ecological succession

climax community

the stable, living part of an ecosystem, in which populations exist in balance with one another and with the environment

biome

A group of ecosystems that share similar climates and typical organisms

climax vegetation

the vegetation that becomes dominant and stable after years of evolutionary development

climax animal population

determined by the climax vegetation, and is the stable animal population

epiphytes

plants that grow on other plants

permafrost

An impermeable, permanently frozen layer of soil

temperate deciduous forest

a forest (or biome) that is characterized by trees that shed their leaves in the fall; has four distinct seasons

temperate coniferous forest

forest (biome) that is cold, dry, and inhabited mainly by trees that do not lose their leaves

taiga

biome of the north with long cold winters and trees that do not shed their leaves; thin soil covered in moss and lichens

tundra

a treeless, frozen plain found between the taiga and the northern ice sheets; permafrost

marine, freshwater

two types of major aquatic biomes

intertidal zone

the region exposed at low tides that undergoes variations in temperature and periods of dryness

neritic zone

the region on the continental shelf that contains ocean with depths up to 600 feet and extends several hundred miles from the shores

pelagic zone

the region typical of the open seas; an be divided into photic and aphotic zones

plankton

passively drifting masses of microscopic photosynthetic and heterotrophic organisms

nekton

active swimmers such as fish, sharks, or whtles that feed on plankton and smaller fish

diatom

an alga that is the chief autotroph

benthos

organisms that live attached to or near the bottom of the ocean floor

turgor

plant cells have rigid cell walls and thus build up cell pressure called _____ as water flows in; this pressure counteracts the gradient pressure, stops the influx of water, and established water balance

holdfasts

Root like structures that some organisms have to help them hold on to rocks in currents