ECOSYSTEM Flashcards
what is an ecosystem?
the relationship between all living and non-living components of a habitat
what are the component of an ecosystem?
Habitat = place where organism lives
Population = all of the organism of one species, who live in the same place at the same time, who can breed together
Community = all the populations of different species, live in the same place at the same time
what are two characteristic of ecosystems?
vary in size
very dynamic
what are the 2 groups of factors affecting ecosystem?
abiotic and biotic factors
list biotic factors
producers
consumer (primary, secondary and tertiary)
decomposers
predation
competition
hunting
list abiotic factors
light
temperature
pH
what are 3 types of change in ecosystem that affect population size?
cyclic changes - changes repeat themselves in a rhythm (tides), the way in which predator and prey species fluctuate is cyclic
directional changes - changes are not cyclic
unpredictable/erratic changes - have no rhythm and no constant direction
what is biomass?
mass of all living materials in an ecosystem
what is the first source of energy in an ecosystem?
sunlight.
explain what happens to sunlight?
only a small percentage of light (1-3%) is absorbed by plants and used by them. The rest of the sunlight might not be absorbed to to light not hitting the chloroplast or due to wrong wavelength of light which makes it reflect.
what is total amount of energy USED by the plant to make biomass called?
gross production
what might be the energy use for in plants?
for respiration
what is meant by net production?
the remaining energy, the energy that is going to be transferred to the next consumer
how is net production calculated?
gross production - respiratory losses
how do consumers get energy?
by ingesting producers, however only 10% of th energy is transferred to the consumer as some of the biomass might be digested and released into faeces, urine and respiration, released as heat.
less available at higher trophic levels
what is the formula to calculate ecosystem efficiency?
(biomass transferred : biomass intake) x 100
(biomass at higher level : biomass at lower level) x 100
(biomass of primary consumer : biomass of producer) x 100
what makes up the biomass?
organic and inorganic components
what is a trophic level?
each level in the food chain
what is meant by productivity?
the rate at which energy passes through each trophic level in the food chain
what is gross primary productivity ?
the rate at which plant convert light energy into chemical energy
how do human manipulate environmental factors to increase the amount of biomass in plants?
- grow plant under light banks and crops planted early to provide longer growing season to harvest more light , thus increasing the rate o photosynthesis and biomass production
- grow plant in greenhouses which provides warmer temperature increasing photosynthesis rate and biomass production
- crop rotation can stop the reduction of inorganic materials in soil (nitrate or potassium), thus plant will have more nutrients available to carry out more photosynthesis
- use of pesticides and fungicides and herbicides to kill insects that may feed on plants removing biomass from food chain
-competition of weed for light, water and nutrients, reduces crop
how do human manipulate environmental factors to increase the amount of biomass in animals?
- harvesting animal just before adulthood
-selective breeding to produce improved animal
-animals treated with antibiotics to avoid unnecessary loss of energy
- preventing animals from moving to look for food, food is directly supplied to them and environmental temp is kept constant
why does the carbon cycle occur?
because there is a limited availability of carbon, therefore it is recycled
describe the carbon cycle.
-carbon dioxide present in the atmosphere
-carbon dioxide uptaken by plants
-carbon dioxide is used for photosynthesis
-carbon dioxide is converted into carbon containing compounds = carbon fixation
-carbon dioxide is also released into the atmosphere via respiration
-consumers feed off from producers, therefore the carbon containing compounds are passed on the food chain
-consumers also release carbon dioxide via respiration
-when producers and consumers die, the carbon containing compound remain in their waste matter.
-these waste matters and compound are broken down by decomposers in a process called decomposition , this process releases carbon back in the atmosphere
- the waste matters that are not decomposed become fossil fuels
- when fossil fuels are burnt, via the process of combustion, this releases carbon dioxide into the atmosphere.
what is the process of converting nitrogen gas into ammonia called?
nitrogen fixation
what are the bacteria that carry out nitrogen fixation called? give 2 examples
nitrogen-fixing bacteria : Azotobacter (lives freely in the soil) ( nitrogen gas- ammonia - ammonium ions)
rhizobium ( roots nodules) ( nitrogen gas - ammonia)
in what condition can nitrogen fixation occur?
anaerobic conditions
what is the process of converting ammonium ions into nitrate known as? describe the steps
denitrification : ammonium ions - nitrite - nitrate
by what type of bacterias is nitrification carried out? give example in each step
nitrifying bacteria.
ammonium ions into nitrite = nitrosomonas
nitrite into nitrate = nitrobacter
what is required for nitrification, why?
oxygen - bacteria need oxygen for aerobic respiration to ensure their survival, oxygen used in nitrification
how is nitrogen returned to the soil?
by death and excretion of plants and animals
what happens to dead organisms and excretion containing nitrogen? and what does it result to?
broken down by decomposers (saprobionts) , results in ammonia formation
what happens to ammonia?
released into the soil to make ammonium ions
what is ammonification?
the process of obtaining nitrogen form the decomposition of dead organism and excretion, producing ammonia which is then converted into ammonium ions
how is thereduction of nitrogen gas availability in the atmosphere avoided?
by the process of denitrification
explain the process of denitrification
denitrifying bacteria convert NITRATE into nitrogen gas in anaerobic conditions
when can denitrifying bacteria carry out denitrification?
when they carrying out anaerobic respiration
what processes can occur under anaerobic conditions?
nitrogen fixation an denitrification
what processes reduce or oxidise nitrogen?
nitrogen fixation - reduction
nitrification - oxidation
denitrification - reduction
what is succession in ecosystem?
when a habitat/ ecosystem changes from simple to complex over time
how does succession occur?
via seral (intermediate) stages.
what is the first stage of seral stages, describe it.
PRIMARY SUCCESSION : when there is an inhabited land, which is colonised by an initial species (mousse or lichen - PIONEER SPECIES), usually in the form of seeds or spores
these species are often adapted for colonisation eg tolerant to extreme conditions and reproduce asexually.
-primary succession
what do pioneer species cause?
change the environment making it less hostile and enabling the survival of other species
what is the second stage of seral stages?
INTERMEDIATE COMMUNITY : the growth of an intermediate community such herbs and grass, shrubs and trees.
When these intermediate organisms decompose, they release nutrients into the soil making the environment less hostile
secondary succession
what is the last stage of seral stages?
CLIMAX COMMUNITY - when the environment becomes stable and no more succession occurs,present at the end of primary succession
what is meant by deflected succession?
when human activities interfere or stop succession, such as agriculture and farming.
the habitat doesn’t reach t eh climax so it is called plagioclimax community.
what is primary succession?
colonisation of uninhabited terrain over time by a living organism
what is secondary succession?
recolonisation of an area after earlier community has been removed
pioneer species
A species that can colonise barren terrain.
ways to measure / sample ecosystem
using quadrants and transects
what can be calculated using quadrants?
abundance and distribution of species
what should be decided before starting to sample? (quadrants)
- where to place the quadrats : to random sampling , coordinates , systematic sampling at regular distance
- how many samples to take : take samples from across the habitat, make a cumulative frequency against quadrat number. The point where the curve levels off tell you how many quadrants to use
what is the equation to estimate the size of the population of each species in the whole habitat?
mean number of individual of the species in each quadrat : fraction of the total habitat area covered by a single quadrat
what method of sampling is used to look for changes in abundance and distribution of a species across a habitat?
transect
what are the 2 approaches of using a transect?
line transect =at regular intervals make a note of which species is touching the tape
belt transect = at regular intervals , place a quadrat next the line (interrupted belt transect) , or place a quadrate and move it along the line (continuous belt transect)
