Key Definitions - Ecology and the environment Flashcards
define abiotic factors.
non-living parts of an ecosystem, e.g. temperature, light intensity, moisture, wind speed, soil pH, mineral concentration, carbon dioxide and oxygen levels
define biodiversity.
variety of living organisms in an ecosystem. It takes into account the number of different species and the population of each
define biotic factors.
living components of an ecosystem, e.g. food availability, pathogens, predation and competition (interspecific competition – competition between members of different species and intraspecific competition – competition between members of the same species)
define community.
all the populations of different species living together in a particular place at a particular time
define distribution.
spread of living organisms in an ecosystem, affected by environment changes
define ecosystem.
the community of organisms (biotic) and non-living components (abiotic) of a particular area and how they interact with one another
define habitat.
the place in an ecosystem when an organism lives
define population
all the organisms of the same species living with one another in a habitat at any one time
define decomposers.
organisms that release enzymes which speed up the breakdown of dead plant and animal material, e.g. bacteria and fungi
define decomposition.
the breakdown of dead materials into simpler organic matter that can eventually be absorbed by plants. The rate at which it occurs is affected by temperature, water and oxygen content
define energy transfers.
the flow of energy from one trophic level to the next. Is never 100% and decreases the further you move up the food chain due to not all of the organism being eaten, not all of it being digested, some of the energy being used in respiration/movement of the organism and some energy being lost in the excretory products
define food chain.
shows the feeding relationships between organisms and the stages of biomass transfer. The arrows represent the flow of energy between organisms
define food web.
network of food chains that shows how energy can flow in different ways and that animals can feed on more than one organism
define primary consumer.
herbivores that consume producers in a food chain
define producers.
photosynthetic organisms at the start of the food chain that provide biomass for all the organisms in the food chain
define pyramid of biomass.
a pyramid, with each layer of the pyramid representing the amount of mass of living material at each trophic level of a food chain. When asked to draw one in exams, they often start off bigger at the bottom and get smaller at each level above
define pyramid of number.
a pyramid showing the numbers of each organisms at each trophic level, often looking similar to the pyramid above but if the producer is large and small in number, like a tree, can look quite different
define quadrat.
a square grid used to sample populations and to determine abundance and distribution of organisms in an ecosystem
define quaternary consumers.
carnivores that consume tertiary consumers
define secondary consumers.
carnivores that consume primary consumers
define tertiary consumers.
carnivores that consume secondary consumers
define apex predator.
an organism in a food chain/web that is not consumed by another
define trophic level.
the position of an organism in a food chain. Only around 10% of the energy is transferred from one level to the next
define carbon cycle.
the cycle where carbon moves between organisms and the environment, namely in the form of carbon dioxide and involving respiration, photosynthesis, fossilisation and combustion
define decomposers in the nitrogen cycle.
organisms that release enzymes that catalyse the breakdown of dead plant and animal material releasing nitrogen containing compounds such as ammonia into the soil.
define denitrifying bacteria.
bacteria that convert nitrates in the soil into nitrogen gas. Occurs when conditions are anaerobic and can be prevented by ploughing the soil to aerate the soil and having good drainage to prevent the air spaces from filling with water, both ensuring there is adequate amounts of oxygen to prevent the growth of these organisms
define nitrifying bacteria.
aerobic organisms that convert ammonia to nitrites and then nitrates which can be absorbed by plants using active transport in the roots
define nitrogen cycle.
the cycle through which nitrogen moves between living organisms and the environment
define nitrogen fixing bacteria.
bacteria that convert nitrogen gas into nitrogen containing compounds that plants can use. Can be free living in the soil or found in root nodules of leguminous plants (clover, peas) where they have a mutualistic relationship and convert nitrogen gas to nitrogen containing compounds which the plant receives and in return get sugars from the plant that have been produced via photosynthesis
define deforestation.
removal of trees to use the resources on the tree for fuel or for space that the trees occupy
define eutrophication.
pollution of water by fertilisers being added in nearby land and nutrients leaching into the water causing excessive growth of algae at the surface of the water (algal bloom), which prevents light reaching photosynthetic plants at the bottom of the water, causing them to die, reducing the oxygen levels in the water and eventually resulting in the death of all aerobic organisms in the water
define global warming.
rise in average temperatures on earth due to increased levels of greenhouse gases like carbon dioxide, causing the enhanced greenhouse effect where more heat is trapped in the atmosphere and once reflected off the surface is reflected back to the surface rather than escaping
define greenhouse gases.
gases in the earth’s atmosphere that trap heat and cause the greenhouse effect, examples being water vapour, carbon dioxide, methane, nitrous oxide and CFCs
define leaching.
movement of nutrients e.g nitrates in the soil into lakes and rivers due to rain and can lead to eutrophication
define pollution.
contamination or destruction of the environment due to human impacts
