Module 6.5 Flashcards
Ecosystems
what is an ecosystem
all the populations of animals plants fungus and bacteria interrelating with the physical and chemical environment of the habitat - influence by both biotic and abiotic factors
what is a habitat
the place where an organism lives
what is a population
all of the organisms of one species who live in the same place at the same time and who can breed together
what is a community
all the populations of different species who live in the same place at the same time and who can interact with each other
what are biotic factors in an ecosystem
the living organisms within the ecosystem
example of biotic factors
producers
consumers
decomposers
what are abiotic factors
non-living components of an ecosystem
example of abiotic factors
pH
humidity
temperature
concentration of pollutants
why are ecosystems described as dynamic
as the no-living elements change and the living elements frow and died with populations of particular species rising and falling
what are cyclic changes in ecosystems
changes that repeat in a rhythm e.g. movements of tides
the may and which predator prey species fluctuate is cyclic
what are directional changes in ecosystems
changes go in one direction and tend to last a long time
e.g. erosion of a coastline
what are unpredictable/erratic changes in ecosystems
have no rhythm or constant direction
e.g. the effect of lightning or hurricanes
examples of how ecosystems vary in size
rock pool
field
large tree
what is biomass transfer
transfer of biomass from one trophic level to another
what is a trophic level
the level at which an organisms feeds in a food chain
how do plants make up their biomass
energy captured in photosynthesis to produce organic molecules
some of the products of photosynthesis used immediately for respiration while some are incorporated into tissues and organs
inorganic components such as mineral ions combine with the organic molecules to make the biomass
how is the biomass from producers transferred to consumers
when a plant is eaten its biomass is consumed by the primary consumer
how is biomass lost through life processes
organisms need energy to carry out life processes
respiration releases energy from organic molecules like glucose
some of this energy is converted to hear and materials are lost in carbon dioxide and what
how is biomass lost through waste
dead organisms and waste material is lost from a food chain which is then only available to decomposers
waste material includes parts of animals and plant that cannot be digested by consumers such as bones and hair
what is a pyramid of number
represents how in a food chain where organisms about the same size there will be a large amount of producers and fewer consumers as you go up the trophic levels
each bar represents the number of individuals
what is a pyramid of biomass
provides a more accurate picture of how much biomass exists at each level that a pyramid of numbers
each bar is proportional to the dry mass of all the organisms at that trophic level
calculation for efficiency of biomass transfer
biomass transferred/biomass intake x 100
biomass at the higher trophic level/biomass at the lower trophic level x 100
what is productivity in an ecosystem
the rate of production of new biomass by producers
what is gross primary productivity
the rate at which plants convert light energy into chemical energy through photosynthesis
why is gross primary productivity inefficient
not all of the energy from the sun is used
not all of this energy is involved in glucose production
not all of the glucose produced is used for production of biomass contributing to growth e.g. starch and cellulose
what is net primary productivity
the amount of energy from the sun that remain to enter the food chain
how can humans increase net primary productivity
make energy conversion more efficient
reduce energy loss
increase the amount of biomass incorporated into plants
examples of increasing primary productivity
growing crops under light banks
irrigation
growing in greenhouses
crop rotation and fertiliser
pesticides
herbicides
fungicides
what is gross secondary productivity
the amount of biomass and energy transferred from producers to consumers through consumption
why is gross secondary productivity inefficient
consumers do not make full use of plants biomass
some plants die
not every part of the plant is eaten
not everything is digested
why is net secondary productivity inefficient
a large amount of the biomass digested in respired as consumer are metabolically active
only a small amount of energy contributes to a increase in biomass which can be transferred to the next consumer in the food chain
how can humans manipulate secondary productivity
harvesting animals just before adulthood - in adulthood not much energy is dedicated to growth
selective breeding for increased growth rate or egg/milk production
antibiotic treatment
zero grazing
keeping temperature constant
what are the 4 stages of the nitrogen cycle
ammonification
nitrogen fixation
nitrification
denitrification
what bacteria is responsible for nitrogen fixation in free soil
azotobacter
what is nitrogen fixation
taking nitrogen gas from the atmosphere and “fixing” it into ammonium ions or nitrate ions
what bacteria is responsible for nitrogen fixation in root nodules
rhizobium
what plants are nitrogen fixing
legumes e.g. peas, beans and clover
how do rhizobium and nitrogen fixing plants have a mutualistic relationship
the bacteria provide the plant with fixed nitrogen and receive carbon compounds such as glucose in return
what is leghaemoglobin
protein similar to haemoglobin that is in the root nodules to absorb oxygen keeping the conditions for rhizobium anaerobic to allow for nitrogen fixation
what bacteria’s are responsible for nitrification
nitrobacter and nitrosomonas
what is ammonification
where decomposers break down organic nitrogen compounds e.g. proteins into ammonia or ammonium ions
what does nitrosomonas bacteria do
oxidises ammonium ions to nitrites
what do nitrobacter bacteria do
oxidise nitrites to nitrates
what is nitrification
when bacteria convert ammonium ions or ammonia into nitrites then nitrates
what is denitrification
when bacteria convert nitrates back into nitrogen gas
what do animals, plants and microorganisms contribute to the carbon cycle
as they respire they release carbon dioxide
microorganisms decompose organic waster
what do plant contribute to the carbon cycle
terrestrial plants use gaseous carbon dioxide in photosynthesis
aquatic plants use dissolved carbonates
how is carbon exchanged between the air and water
carbon dioxide dissolves in water and forms carbonic acid
weathering of limestone and chalk provides releases hydrogen carbonate into rivers
how do fossil fuels contribute to the carbon cycle
combustion of fossil fuels increases the amount of atmospheric carbon dioxide
what is succession
progressive change in a community of organisms over time
what is a pioneer species
the species that begin begin the process of succession often colonising an area as the first thing living there
what is a climax community
the final stable community that exists after the process of succession has occurred
what is primary succession
the development of a community from bare ground
what is the pioneer species in sand dunes and what do they do
sea rocket
tolerates salt, lack of fresh water and unstable sand
sand builds up around their base forming mini sand dunes and nutrients from dead and decaying plants enter the sand allowing for bigger plants to colonise
example of what species can colonise after sea rocket and what they do
sea couch grass
has underground stems to stabilise the sand
marram grass
shoots trap wind blown sand
nutrients build up as more plants colonise
example of leguminous plants which can colonise sand dunes after sea couch grass and marram grass
hares foot clover
convert nitrogen to nitrate allowing more species to colonise and further stabilise the dune until a climax community is reached
what is deflected succession
when succession is stopped or interfered with so often does not reach a climax community
example of how deflected succession can occur
mowing grass
grazing
application of fertiliser or herbicide
what do deflected succession communities reach instead of a climax community
plagioclimax
what is sampling
selecting small portions of a habitat and studying them carefully to try and get an accurate estimate of the number of individuals of every species in a habitat
what is distribution of a species
presence or absence of a species
what is abundance of a species
number of individuals of each species
how can distribution and abundance be measured
quadrats
how to calculate population size of a species from a quadrat
mean number of individuals of the species in each quadrat / fraction of the total habitat area covered by a single quadrat
what is a transect
a line taken across a habitat
what is a transect used for
looking at changes in vegetation across a habitat
what are the two types of transect
line transect
belt transect
