Ecology Flashcards
what is biodiversity
the amount of variation shown by organisms in an ecosystem
what is a food chain
a chart showing the flow of energy from one organism to the next beginning with a producer
what is a producer
an organism that makes its own organic nutrients usually using energy from sunlight through photosynthesis
What is a consumer
an organism that gets its energy by feeding on other organisms
what is a community
All the populations of different species living in a habitat
what are habitats
the place where an organism lives
what are decomposers
an organism that gets its energy from dead or waste organic matter
what is an ecosystem
All the biotic and abiotic factors, interacting together, in a given area at one time
what are trophic levels
the position of an organism in a food chain or food web
what is a population
the total number of organisms of the same species living in a habitat
what is a biome
areas of our planet that have similar climates, landscapes, organisms. It is a large ecosystem consisting of many habitats
what are food pyramids of numbers
number of organisms in each trophic level in a food chain
what are food pyramid of biomass
total mass of organisms on a trophic level, representing the amount of chemical energy that is stored in living tissue
what is fresh biomass
living organisms
what is dry biomass
mass of plant/animal after water has been removed
what are pyramids of energy transfer
shows the rates of energy flow through trophic levels, not absolute amounts of energy stored. It can have energy units, such as kCAL/m²/yr
how is energy transferred along a food chain
-sunlight energy is converted into chemical energy by plants via photosynthesis
-chemical energy is stored as living matter(biomass)
-when an organism is consumed, biomass is passed along a food chain which means that energy is passed along too
-pyramids of biomass are almost always pyramid shaped as not all biomass is moved from one trophic level to another, so biomass is lost at each stage of the pyramid
why is only 10% of energy from each trophic level passed on to the next
-respiration
-lost in faeces and excretory compounds such as urea. this is passed on to detritivores and saphrotrophs
-energy is used in life processes like moving
-lost as some parts of organisms are not eaten
what is the method for using a quadrat
-randomly assign random coordinates
-place quadrates at chosen coordinates
-count the number of plants in each quadrat
-find average number of plants from quadrat samples
-work out how many quadrats would fit in marked out area
-used this to estimate the number of plants in your marked out section by scaling up your average
how is respiration related to the carbon cycle
it produces carbon dioxide from organic compounds as they are broken down to release energy
How is photosynthesis related to the carbon cycle
photosynthesis fixes carbon atoms from CO2 into organic compounds
how is fossilisation related to the carbon cycle
it occurs when living thing don’t decompose completely. Fossil fuels are formed (coal, oil, natural gas)
how is combustion related to the carbon cycle
combustion releases CO2 into the atmosphere when fossil fuels are burned
how is feeding and assimilation related to the carbon cycle
feeding and assimilation pass carbon atoms already in organic compounds along the food chain
how is decomposition related to the carbon cycle
it occurs in aerobic situations, decomposers break down dead organisms and the carbon is released through respiration
how are excretory products related to the carbon cycle
the excretory products are broken down by decomposers
how is decay and excretion related to the carbon cycle
Decay and excretion pass carbon atoms from one organism to the next
what is an abiotic factor
a physical or chemical factor affecting an ecosystem
what is a biotic factor
A living factor affecting an ecosystem
what are examples of biotic factors
-predation
-paratism
-diseases
-presence of pollination insects
-availability of nest sites
what are examples of abiotic factors
-climate(temp, light intensity, water availability etc)
-hours of daylight
-soil conditions
-pollution
how is assimilation related to the nitrogen cycle
-animals eat plants, taking on their compounds that are usually in the form of protein
-most of this goes into increasing the animal’s biomass(and for tissue growth/repair
how is death and excretion related to the nitrogen cycle
-in animals some nitrogen is excreted in the faeces(as urea and ammonia).
-All living organisms die, so their nitrogen compounds are recycled
how is decomposition related to the nitrogen cycle
-dead organisms are broken down by decomposers.
-This includes bacteria that live in the soil
-Turns nitrogen(N2) in protein to ammonium
how is nitrification (oxidation by nitrifying bacteria) related to the nitrogen cycle
-some bacteria in the soil convert ammonia into Nitrite(NO2-), then Nitrate(NO3-)
-These bacteria are known as nitrifying bacteria
how is denitrification (break down by denitrifying bacteria) related to the nitrogen cycle
-Other bacteria break down ammonium in the soil to form nitrogen gas
-This are then released into the air
how is nitrogen fixation by free soil bacteria and lightning related to the carbon cycle
-nitrogen gas is inert, but lightning can provide enough energy for it to react with oxygen-forming nitrous oxide(dissolves in rain)
-There are also free-living bacteria with enzymes capable of converting nitrogen gas into nitrates
how is nitrogen fixation by root nodule bacteria related to the carbon cycle
-some plants have nitrogen-fixing bacteria that live in their roots inside nodules-plants that have these are called legumes (e.g. peas)
-The nitrogen fixing bacteria can capture the unreactive nitrogen gas in the atmosphere and convert it into a form the plants can use
absorption by the roots
-nitrates can be absorbed into the plant via the roots (through a process called active transport). The plants can use -these to make protein as they are more reactive than nitrogen
-root hair cell
what is deforestation
the clearing of natural forest by burning or logging to allow an alternative use of the land
what are reasons for deforestation
-agriculture
-construction/housing
-making paper + furniture
-fuel to burn
-make way for roads
what are the effects of deforestion
-desertification
-fewer trees and less natural habitats
-reduction in food for species
-disturbance of the water cycle(less transpiration can lead to flooding/drought)
-contributes to global warming as there are less trees which would be photosynthesizing
-soil erosion
how can deforestation be mitigated
-reforestation
-implementation of laws to limit deforestation
What is a food web
A network of interconnected food chains showing the energy flow through part of an ecosystem
what is the greenhouse effect
-short wave length ultraviolet radiation radiates from the sun and reaches earth
-Some is absorbed by Earth’s surface and emitted again as longer wavelength infrared radiation
-Greenhouse gases absorb and re-emit some of this long infra-red radiation, which would otherwise escape into space
-This then heats up the surface of the Earth
-Human activities are polluting the atmosphere with extra greenhouse gases such as carbon dioxide
what are the effects of Global Warming:(only a few degrees rise)
-ocean temps increasing, causing melting of polar ice caps -> rising sea levels -> flooding
-increasing temps causes extreme weather like super storms, flooding, droughts
-changes in or loss of habitats due to these extreme weather events
-decreases in biodiversity as food chains are disrupted and extinction rates increase
-increases in migration of species to new places, including increased spread of pests and disease
soil erosion
-tree roots hold soil together
-when tress are removed, soil can be washed away by the rain, leaving infertile land, due to the loss of soil minerals and nutrients
leaching
-trees take up nutrients from the soil before they can be washed away by the rain, but return to the soil when leaves die
-when trees are removed nutrients and soil minerals get leached away but do not get replaced, leaving infertile soil
disturbance of evaporation by deforestation
The removal of trees reduces the release of water vapour into the atmosphere by transpiration, reducing cloud formation and rainfall
how does deforestation disturb the balance of carbon dioxide and oxygen
The removal of trees reduces photosynthesis, so less carbon is removed from the atmosphere and stored in plant tissues
Combustion of felled trees increases release of carbon dioxide into the atmosphere
Less plants are consumed, so less decomposition of plants
why do farmers frow legume plants such as clovers then plough them into the soil before growing other crops
-root nodules in the legumes
-nitrogen fixing bacteria fixes nitrogen gas into nitrates/ammonia
-these are used to make proteins/amino acids for growth.
-the decomposition of the legumes also turn the legumes into ammonia
eutrophication
-fertilisers are washed off the land by rain
-fertilisers containing nitrates end up in freshwater ponds or rivers
-algae form algal bloom as nitrates level rise. algae reproduce rapidly
-algae prevent light reaching the plants at the bottom of the pond
-plants cannot photosynthesise and therefore die
-algae also die as they run out of nitrates
-bacteria decompose large quantities of dead plants and algae
-bacteria reproduce. Level of respiration increases due to large microorganisms
-bacteria use up all oxygen in water(water become anoxic). Other pond life dies
sewage pollution
-sewage is washed into waterways
-growth of aerobic bacteria which feed on biological waste
-reduce the availability of dissolved oxygen in water
-aquatic organisms that are sensitive to oxygen levels die, leaving only organisms that can survive at low concentrations of oxygen
-aquatic ecosystem decreases in biodiversity
-also increase in pathogenic bacteria
similarities between eutrophication and sewage
-decomposers/bacteria respire and grow in numbers
-water becomes anoxic in both
-both causes death of aquatic organisms
differences between eutrophication and sewage
-eutro. is due to nitrate fertilisers/ sewage for other
-eutro. involves algal bloom, sewage does not
-eutro. starts with decomposition of aquatic plants, sewage is decomposed in other
How is carbon dioxide released into the atmosphere
-car exhausts
-industrial processes like burning fossil fuels
-cutting trees down affects carbon dioxide levels
How is methane gas produced
-rotting plants in marshland
-rice growing and cattle rearing
How is nitrous oxides released
-released by bacteria in soils and the ocean
-more released from soils after fertiliser used
-released from vehicle engines and industry
How are CFC produced
-chlorofluorocarbons
-old fridges and aerosol sprays
How is carbon monoxide form
Burning of fossil fuels without enough air supply
Negative impacts of carbon monoxide
-combines with haemoglobin in red blood cells and prevents them from carrying oxygen
-cars fitted with catalytic converters to turn carbon monoxide produced in cars into carbon dioxide
How is acid rain formed
-Sulfur dioxide formed from sulfur impurities in fossil fuel sources and
-it mixes with rain clouds to form dilute sulfuric acid
-falls as acid rain
-internal combustion engines in cars and power stations are main causes of acid rain
Carbon flux
The movement of carbon from one carbon sink to another
Carbon sink
An object or environment that can absorb carbon dioxide from the atmosphere, absorbing more than it releases
Pollution
The contamination of the environment by harmful substances that are produced by the activities of humans
