6.6 ecosystems Flashcards
define ecosystem
a community of animals, plants and bacteria interrelated with the physical and chemical environment
define habitat
a place where an organism lives
define population
all of the organisms of one species who live in the same lace at the same time and can breed together
community
al the populations of different species who live in the same place at the same time and can interact with each other
define biotic factors
environmental factors associated with living organisms in an ecosystem that affect each other
give 6 examples of biotic factors
producers
consumers
decomposers
predation
disease
competition
define abiotic factors
non-living components of an ecosystem that affect other living organisms
give 6 examples of abiotic factors
light intensity
soil pH
water availability
humidity
temperature
concentration of pollutants
why are ecosystems referred to as dynamic
because ecosystems are changing
what are the three types of changes in an ecosystem that affect population size
cyclic changes
directional changes
unpredictable changes
define cyclic changes
changes that repeat themselves in a rhythm
give an example of a cyclic change
tides
predator and prey relationship
define directional changes
changes that aren’t cyclic and go in one direction. They tend to last longer than the lifetime of organisms with the ecosystem
give an example of a directional change
erosional processes
depositional processes
glaciation
define erratic changes
theses changes have no rhythm or constant direction
give examples of erratic changes
hurricane
earthquake
tsunami
define biomass transfer
transfer of biomass from one trophic level to another
define trophic level
the level at which an organism feeds in a food chain
how is biomass lost in a food chain
dead organisms
not all of the animal being eaten
respiration
senses
reproduction
heat energy
what is the trend in biomass as you go up a food chain
biomass is less at higher levels
what is biomass
dry mass of the organism
How is biomass obtained by scientists
drying the organism by putting it in an oven to evaporate all of the water
how do you calculate the ecological efficiency of the transfer of biomass
(biomass at higher trophic level/biomass at lower trophic level)*100
define productivity
the rate of production of new biomass by producers
define gross primary productivity
the rate at which plants convert light energy into chemical energy through photosynthesis
define net primary productivity
the rate at which energy is stored as biomass by the producer that is available for the next consumer
what is the difference between primary and secondary productivity
primary - plant
secondary - animal
how can we make energy conversion more efficient when farming plants
greenhouses
fertiliser
light banks
pesticides
crop-rotation
How cans humans manipulate energy transfer when farming animals
battery farming
antibiotics
killing them young
selective breeding
how do saprotrophs eat?
they secrete enzymes on dead or waste material which digest the material into smaller pieces which are then absorbed into the saprotroph’s body
why are bacteria and fungi vital for recycling within ecosystems
if bacteria and fungi did not break down dead organisms, energy and valuable nutrients would remain trapped within the dead organism
why do living things need nitrogen?
to make proteins and nucleic acids
what kind of nitrogen do plants require
fixed nitrogen (NH4+,NO-)
how is fixed nitrogen produced
lightning and the Haber process only makes up about 10% of fixed nitrogen the rest is by bacteria
how much of the atmosphere is made of nitrogen
79%
what bacteria fix nitrogen
Azotobacter
Rhizobium
Describe the role of Azotobacter
bacteria that lives freely within the soil and fix nitrogen gas, which is in the air within the soil, using it to manufacture amino acids
what is the role of Rhizobium
lives inside the root nodules of leguminous plants and is nitrogen fixing
It has a mutualistic relationship with the plant by supplying it with fixed nitrogen and receiving carbon compounds such as glucose
what is the role of leghaemoglobin
absorbs oxygen to keep conditions anaerobic for nitrogen reductase
What is ammonification
organic nitrogen in soil and urea —> NH4+ by bacteria involved in putrification
what is nitrification
chemoautotrophic bacteria in soil oxidise ammonium ions to nitrite ions and the into nitrate ions
What is the role of nitrosomanas
oxidising ammonium ions to nitrite ions(nitrification)
What is the role of Nitrobacter
Oxidise nitrite ions to nitrate ions (nitrification)
Whet is denitrification and its conditions
occurs in anaerobic conditions such as waterlogged soils and use nitrates as a source of oxygen to produce nitrogen gas and nitrous oxide
define climax community
the final stable community that exists after the process of succession has occurred
define deflected community
happens when succession is stopped or interfered with such as by grazing or lawn mowing
define pioneer species
the species that begins the process of succession
define succession
progressive changes in a community of organisms over town
