Energy And Ecosystems Flashcards
What is an ecosystem?
A group of living organisms and non living things and the interrelationships between them
What are worms bacteria and fungi all examples of?
Decomposers or detrivitours
S__________ are a type of decomposer
Saprobionts
Why is measuring biomass somewhat inaccurate? What is done to improve accuracy?
Different organisms will have varying levels of water at any one time
Use dry mass
What is dry mass measured in?
gm^-2 on land
gm^-3 in air or water
What is an alternate way of measuring biomass to simple weighing ?
Bomb calorimetery
Burn sample in a water bath, measure the temperature change within the bath
Give the percentage of the suns energy converted by plants
Why is it so low?
1-3%
90% relfected by clouds
Chlorophyll cant absorb all wavelengths
Requires light to hit chlorophyll may just miss
Give four factors that make consumers inefficient within a food chain
Respiration
Faeces
Urine
Not all of them are consumed e.g. Bones
What is gross production?
The total amount of energy converted into organic matter
What is net production?
The amount of energy available to the next trophic level
How do you work out net production?
Gross production - respiratory losses
Give three general effects that come from the inefficiency of food chains
Max 5 trophic levels
Higher levels have reduced biomass
Reduced total energy at higher levels
How do you work out the percentage efficiency of the movement up a trophic level?
(Energy available after / energy available before) x 100
Give the down falls of a pyramid of number
Not accounted for size or biomass
So varrying that comparison is impossible
Give the downfalls of a pyramid of biomass
The organisms must be killed
Small sample = unrepresentative
Not all year round doesnt show seasonal variation
What is the basic role of agriculture?
To increase productivity
How does agriculture attempt to increase gross primary production? ( i.e. In plants)
Increase light levels = plants grow all year
Increase water levels through irrigation needed for dependent reaction
Increase temperature= faster photosynthesis (to extent)
How do you decrease respiratory losses in live stock?
Restrict farming
Keep warm
Harvest before adulthood
Why does weeding increase productivity of a crop?
Reduces competition for the crop
More nutrients
Why do pesticides increase net primary production?
Pests damage the crop, this damage needs to be repaired, takes up energy
How is gaseous nitrogen turned inti other nitrogen forms?
Lightening strikes
Harber process
Nitrogen fixing bacteria - reduction of nitrogen to ammonia
What is the process of ammonification?
Where ammonium is produced from ammonium containing molecules e.g. Urea
What type of organisms are responsible for ammonification?
Saprotrophs
Ammonium ions form in the soil due to their release of ammonia
What is nitrification?
Give the steps in which it happens
Nitrifying bacteria
Oxidise ammonium to nitrite ions (NO2-)
The pn oxidised further to nitrate ions (NO3-)
Why is it crucial to have aerobic conditions in agriculture?
Nitrification is an aerobic process
In anerobic conditions denitrifying bacteria flourish
What is a nitrite ion?
NO2-
What is a nitrate ion?
NO3-
What do denitrifying bacteria do?
Produce Nitrogen gas and nitrogen oxides
Why are fertilisers needed?
In crop plants minerals are taken up Plants harvested and removed No decomposition Minerals removed Fertilisation adds minerals back to the soil
What are natural fertilisers?
Dead or decaying organisms or wastes
Bone meal
What are artificial fertilisers?
Where mined rocks or laboratory synthesised chemicals are blended into a mix
Give three problems with fertilisers?
Reduced biodiversity (fastest growing favoured which increases competition for other plants) Leaching rain dissolves nutrients which can percolate into groundwater stores (linked to stomach cancer) Eutrophication
Describe how eutrophication occurs
Lack of NO3- is a limiting factor for algae blooms in rivers
Leaching of NO3- leads to more alage
Growth on surface (algae bloom) limits light to lower depths
Lower plants die as they cant photosynthesise
Saprotrophs feed off dead organisms uses oxygen so [oxygen] reduce
Positive feedback as more dead matter from fish dieing due to anerobic conditions
Further nitrates released from dead organisms
Why is the phosphorus cycle crucial?
Needed within organisms for ATP
How does most phosphorus exist? Where?
Phosphate ions - PO4^3-
Found in sedimentary rock and can hence be removed by erosion
Starting with rocks describe the phosphorus cycle
Erosion removes phosphorus
Into dissolved phosphate ions within water bodies
Plants absorb it
Animals get it through feeding on plants
Animals excrete it - ends up back as dissolved in water supplies
Or forms bones and shells
Bones and shells deposited will either dissolve or form sedimentary rocks
What are mycorrhizae and what do they do?
Fungi that have a mutualistic relationship with plant roots
They increase surface area allowing increased absorption of water and minerals
In return in recives organic molecules
