ecosystems Flashcards
what is an ecosystem?
a;ll the organisms living in a certain area and all the non living conditions found there - abiotic and biotic factors
its a dynamic system as it is changing all the time
what are some abiotic and biotic factors that affect the ecosystem of a rock pool?
biotic factors
many organisms in a rock pool feed on seaweed so competition over this food source can limit the population size of the ecosystem
abiotic factors
tides change the temperature and salinity of an ecosystem- only some organisms can tolerate these conditions
what are some abiotic and biotic factors that affect the ecosystem of a playing feild?
biotic factors
large amounts of producers attract large numbers of organisms that use them as a food source
abiotic factors
rainfall and sunlight affect the growth of producers in the ecosystem
what are some abiotic and biotic factors that affect the ecosystem of a large tree?
biotic factors?
insects such as caterpillars can use the leaves of a tree as a source of food, if they remove all the leaves- defoliation they can dlow growth of the tree or cause its death
abiotic factors
drought conditions can negatively impact the growth of a tree and can even cause death
how does energy enter an ecosystem
energy enters an ecosystem through photosynthesis by producers convderting sunlight energy to chemical energy that can be used by other organisms
how is biomass transferred between trophic levels?
energy/biomass is transferred through living organisms in an ecosystem when organsism eat other organisms - producers are eaten by primary consumers and so on
energy locked up in things than cannot be eaten such ass bones and faeces gets recylced back into the atmsphere by decomposers
what is the equation for efficiency of biomass transfer?
biomass transferred/ biomass intake x 100
how is biomass lost between trophic levels?
organisms use energy in respiration for movement and heat - respiratory loss
parts of biomass produced such as feaces and bones cannot be eaten so energy
indegestible parts eaten pass through organism and come out as waste- faeces.
how is energy lost between light and plants?
plants cannot use all light energy that reaches the leaves as some is the wrong wavelength, some is reflected and some pass straight through the leaves
some light hits parts of the plant that do not photosynthesise
what is net productivity?
the amount of enrgy that is available to the next trophic level
gross productivity - respiratory loss
how can you measure the transfer of energy between trophic levels?
calculate the difference between the amount of energy in each trophic level
measure the dry mass of an organism and multiply by the size of the population
the biomass indicates how much energy is stored so difference in biomass shows energy transferred
what are the issues of measuring energy transfer?
consumers might have taken in energy from sources other than the producer measured
how do human activities increase the energy transfer in plants and in animals?
farmers use methods to increase productivity by increasing the enrgy transfer through an ecosystem
in plants
using herbiicides to reduce competition so crops receive more enrgy
insecticides to kill insects that kill or damage ctops so less biomass is lost
fertilisers used so growth is not limited by abiotic conditions
in animals
1 keep animals, warm / indoors ;
2 reduce animal movement ;
3 feed animals high, protein / energy, food ;
4 vaccination / (routine) antibiotics, for animals ;
5 selective breeding / genetic engineering,
for improved animals ;
6 slaughter just before, mature / full size ;
what is nitrogen fixation?
when nitrogen gas in the atmosphere is turned intp ammonia by bacteria such as rhizobium (in root nodules) and azotobacter (in soil)
what kind of relationship does rhizobium have witha plant?
mutualistic relationship
it provides the plant with nitrogen compounds and the plant gives rhizobium carbohydrates(energy)
what is ammonification?
ammonification is when nitrogen compounds from dead organisms and animal waste are turned into ammonia by decomposers which go onto form ammonium ions
what is nitrification?
nitrification is when ammonium ions in the soil are changed into nitrogen compounds that can be used by plants (nitrates)
nitrifying bacteria called nitrosomas fisrt change ammonium ions into nitrites
then nitrifying bacteria called nitrobacter change nitrites into nitrates
what bacteria is used to convert ammonium ions into nitrites?
nitrifying bacteria called nitrosomas
what bacteria is used to convert nitrites into nitrates?
nitrifying bacteria called nitrobacter
what is denitrification?
when nitrastes in the soil are converted into nitrogen gas by denitrifying bacteria - using nitrates in the soil to carry out respiration under anaerobic conditions to produce nitrogen gas
what is primary succession?
when an ecosystem of newly formed land changes over time (both abiotic and biotic changes)
describe primary sucession
a pioneer species colonises a new land surface. at this point abiotic conditons are harsh and pioneer species only grow if specialised to grow in harsh condtions
-the pioneer species change the abiotic conditons over time, as they die and decompose they produce soil
as conditions become less hostile larger plants are able to colonise
at each stage different plants and animals that are better adapted to the improved conditions move in and outcompete the organisms already there, becoming the dominant species
increased species diversity and biomass
climax community is reached
what is a pioneer species?
the first species that colonises a new area of land
what is a climax community?
the largest and most complex community of plants and animals the ecosystem can support
what is deflected succession?
when human acitivity prevents succession stopping the normal climax community developing, instead a plagioclimax community forms which is different to any of the natural stages of succession
how can distribution of organisms in an ecosystem be measured?
use line transects or belt transects
how is abundance of organisms in an ecosystem measured?
counting the number of individuals in a sample taken - percentage cover can be used for plants
Outline how the percentage efficiency of energy transfer between producers and herbivores
can be estimated.
herbivore / primary consumer,energy x 100 ;
(a sample of) producers collected ;
(a sample of) herbivores /primary consumers
collected;
from the same area ;
(measure) biomass / dry mass (of individual or
population) ;
energy content calculated of producer and
herbivore ;
use of calorimeter / described
what is a trophic level?
a stage in a food chain
Suggest two reasons why the large scale removal of peat from bogs for use in gardens is
discouraged by conservation groups.
bog / habitat / ecosystem, takes a long time to form / hard to replace ;
loss of, biodiversity / rare species ;
