energy and ecosystems and stats test Flashcards
points to write in a null hypothesis
no significant difference
answering a null hypothesis
statistical value is less than the critical value so
accept the null hypothesis
no significant difference
greater than 0.05 probability it is due to chance
the statistical value is greater than critical value so
reject null hypothesis
there is significant difference
less than 0.05 probability it is due to chance
when to do a student t test
looking for differences between two means measured in data
when to do chi squared
finding frequancies
collecting data about individuals in categories
when to do spearmans rank (coralation coefficiant)
looking for a coralation in measurements from the same sample of different varriables
why is only 1-3% of the suns energy converted into organic matter
90% of the suns energy is refelected
not all wavelengths can be absorbed
light may not hit the chorophyll
low co2 may limit rate of photosynthesis
how is energy transfered in the ecosystem
through trophic levels
how is energy lost from the system
heat
excretion - metabloic waste
egestion
not all of the organisum is eaten
how is a calorimetre used to measure chemical energy store
sample is dried by heating in an oven to evapourate water
weigh the sample
put it in a container and set on fire
heat is transfered to the water
thermometre measured temperature
how do you know when all the water is evapourated from a dry sample
when the mass doesnt change after each measurement
how does the stirer in the calorimetre increase acuracy
distributes heat energy around the water
what is gross production
total quantity of energy that the plants in a community convert to organic material
what is respiratory loses
plants use 20-50% of the gorss production energy for respiration leaving little to be stored
what is net production
rate at which plants store energy
net production equation
net production = gross production - respiratory loses
net production of consumer equation
net production of consumer = chemical energy igested - ( chemical energy lost in faeces + respiratory loses to environment)
why do trophic levels rarely have more than 4 levels
biomass is less at higher trophic levels
total energy stored is less at higher trophic levels
insufficiant enrgy makes it up the levels to support a breedign population
where does the main resevoir for phosphorus come from
mineral form in sedimentary rock which originate in the sea but are bought to the surface by geological uplifting, weathering and errosion
phosphorus cycle
phosphate ions in the primary consumer transfer by assimilation to the secondary cnsumer
phosphate is released by saprobionts which decompose dead consumers
the dead material forms sediment rock
phosphate is released by weathering and errosion from the rock
phosphate in the soil is absorbed
repeat
what is a mycorrhizae and what does it do
a fungi that grows around the roots of some plants
they assist in taking up water and mineral ions
they have symbiotic relationships with plants
the fungus produces hypae which increases the surface area if the root tissue so that it can take up more water and minerals
nitrogen cycle
N2 in the air moves by nitrogen fixing to ammonia which dissolves in the soil to form ammonium ions
nitrifying bacteria turns it into nitrite and nitrates
these active transport to the plants which use nitrates and alpha glucose to form amino acids and protiens to feed animals
or
plants die and the nitrogen compounds are digested in ammonificiation by saprobionts to return the nitrogen to ammonia
some nitrates return to the air as nitrogen by dentrification by dentrifyign bacteria in water logged conditions
what is nitrogen fixation
atmospheric nitrogen is fixed when it is combined with oxygen or hydrogen
what is ammonification
saprobionts break down amino acids fro dead material into ammonia and then into ammonium ions
what is nitrification
areobic nitrifying bacteria
oxidise ammonium ions to form nitrites
what are two good soil properties
high oxygen concentration for aerobic respirtaion in nitrifying bacteria
source of nitrogen for ammonification
why are fertilisers needed
intensive farming means biomass is removed so the minerals arent returned to the soil which decreases crop yeild
what are inorganic fertilisers
they are enriched in nitrogen , phosphorus and potasium
easier to predict effect on crops
more concentrated so smaller amounts can be applied
convenient and easier to transport
what are organic fertilisers
made of manure , fishmeal or compost
They prevent soil erosion
Improve water holding properties
Releases nutrients they hold over a long period of time
What is leaching and how does it work
Soluble nutrients are dissolved by rain and carried into the soil out of the reach of plants. The leached nutrients are carried into bodies of water which can lead to eutrophication
How does organic fertilisers reduce leaching
They must be broken down and decomposed by saprobionts
This means there is more time for plants to absorb them
How does leaching effect water bodies
Nutrients enter the water and increase algae production which blocks the sunlight reaching lower plants so less photosynthesis and oxygen concentration decreases. Fish looses food source from dying plants
Pants decompose and co2 increases
Fish die
