General Principles Flashcards
ecology
the study of how organisms interact with one another and with their environment
environment
living portion: biotic component (organisms)
nonliving portion: abiotic component (air, soil, water)
population
a group of individuals of the same species occupying a common geographic area
community
two or more populations reside in the same geographic location
ecosystem
a community and its surrounding abiotic factors
biome
a collection of ecosystems with similar climates and communities
food webs
the flow of energy within an ecosystem by linking together several food chains
autotroph
producer, an organism that begins the food chain by using energy from light/chem. reactions to produce organic compounds from inorganic compounds
heterotroph
consumer, can’t produce its own organic compounds and must consume other organisms to obtain them
detritivore
consumes detritus (dead and decaying organic matter)
decomposer
breaks down dead and decaying organic matter using biochemical reactions
trophic level
each “step” in the food chain
hydrologic cycle
the cyclic movement of water between Earth’s hydrosphere, atmosphere, cryosphere, biosphere, and lithosphere
carbon cycle
the cyclic movement of carbon in different chemical forms from the environment to organisms then back to the environment
nitrogen cycle
the cyclic movement of nitrogen in different chemical forms from the environment to organisms then back to the environment
phosphorous cycle
the cycle that involves the uptake of phosphorus by organisms; phosphorus is found mainly in rocks but natural weathering processes can make it available to biological systems
an essential nutrient for plants and animals in the forms of phosphate ion and hydrogen phosphate ion
constituent of DNA/RNA (ATP/ADP) and lipids
commensalism
an interaction which is beneficial to one species
amensalism
an interaction which is detrimental to one species
antagonism
an interaction beneficial to one species but bad to the other
competition
an interaction that is detrimental to both species
intraspecific
among individuals of the same species
interspecific
between different species
niche
conditions in which an organism lives and the way the organism uses those conditions
competitive exclusion princple
no two species that occupy the same niche can coexist indefinitely; eventually one will be dominant and the other, extinct
can be avoided by having organisms undergo a shift towards different niches
population growth
affects environment through rise in carbon emissions, pesticides and fertilizers, and destruction of habitat
Deforestation
destruction of forest environments for wood or human development.
results in a loss of habitat for many species, therefore hurting biodiversity. The loss of photosynthesis results in less buffering of carbon dioxide levels. A method of clearing forests for agriculture called slash-and-burn involves the burning of vegetation and releases a massive amount of carbon into the atmosphere.
Desertification
Desertification is a type of deterioration of land in which a relatively dry region becomes more and more arid. The primary cause of desertification is the removal of vegetation, which may occur as a result of several factors, such as drought and human activities. The removal of vegetation makes soil more susceptible to erosion. After the topsoil is eroded, infertile soil layers are left to harden into caliche, which hinders further plant growth. The removal of vegetation also results in less evapotranspiration, and therefore even drier conditions.
Many different countermeasures are used to prevent and combat desertification, such as reforestation. Reforestation of certain plants can help enrich the soil and restore its fertility. Reforestation also occurs in the form of windbreaks and woodlots. Windbreaks are rows of trees planted in a way as to provide shelter from the wind, and can help reduce soil erosion and evapotranspiration. Woodlots are like forests, but are generally distinguished by being too small for full-scale commercial harvesting.
survivorship
percentage of remaining survivors of a population over time, usually shown graphically
type 1 survivorship curve
most individuals live out their life span and die of old age (e.g. humans)
type 2 survivorship curve
individuals die at a constant rate
type 3 survivorship curve
most individuals die early in life
