Energy Transfer and Nutrient Cycles Flashcards
Def; ecosystem
a biological community of interacting organisms and their physical environment.
Def; biomass
the chemical energy stored in the plant
Two techniques to measure biomass?
1) Dry mass is the mass of the organism with the water removed
A sample of the organism is dried in the oven set to a low temperature. The sample is then mweighed at regular intervals so when the mass is constant all the water has been removed.
2) Calorimetry
A sample of dry biomass is burnt and the enery realease is used to heat a known volumw of water. The change in temperature of the water is used to calculate the chemical energy of the biomass
Def; Gross Primary Production (GPP)
The total amount of chemical energy converted from light energy by plants in a given area
Def; Net Primary Production (NPP)
The energy available to the plant for growth and reproduction
Def; Respiratory loss
the enery lost to the environment as heat when plants respire
link NPP, GPP, R
NPP = GPP - R
Formula: Net production (N)
(I) Chemical energy ingested in food
F (Chemical energy lost in faeces)
R (Energy lost through respiration)
N = I - (F + R)
Def: decomposers
decomposers break down dead or undigested material, allowing nutrients to be recycled
How to reduce energy loss? (via simplifying food webs)
Insecticides
Herbicides
Parasites
Pathogenic bacteria and viruses
How to reduce energy loss? (via respiratory losses)
limit movement
keep pens indoor and keep warm
Def; saprobionts
organisms that secrete enzymes and digest their food externally, then absorb the nutrients they need.
Def; mycorrhizae
Some fungi form symbiotic relationships with the roots of plants.
Def; hyphae
Fungi which are made of long thin strands which connect to plant roots. This increases the SA of the plant root system. In return the hyphae obtain organic compounds from the plant.
Def; nitrogen fixation
when nitrogen gas in the atmosphere is turned into nitrogen-containing compounds.
what carries out nitrogen fixation?
By bacteria (Rhizobium) that turns nitrogen into ammonia, which goes on to form ammonium ions in solution to be uptaken by plants.
def; ammonification
when nitrogen compounds from dead organisms are turned into ammonia by sapriobionts, which goes on to form ammonium ions.
def; nitrification
when ammonium ions in the soil are changed into nitrogen compounds that can then be used by plants.
what carries out nitrification
Nitrifying bacteria (Nitrosomonas) change ammonium ions into nitrites. The other nitrifying bacteria called Nitrobacter change nitrites into nitrates.
def; denitrification
when nitrates in the soil are converted into nitrogen gas by denitrifying bacteria - they use nitrates in the soil to carry out respiration and produce nitrogen gas.
Explain the phosphorus cycle (4)
1) phosphate ions in rocks are released via weathering into the soil
2) phosphate ions are taken into the plants via the roots, mycorrhizae help the uptake.
3) phosphate ions are lost from animals via feces and are passed down the food chain when they eat each other.
4) when animals and plants die (and via feces), saprobionts are involved in breaking down the organic compounds, releasing phosphates.
Def; guano
Waste produced by sea birds with a high proportion of phosphate ions
process of eutrophication (5)
mineral ions leached from fertilized fields stimulate the rapid growth of algae in ponds and rivers.
2) large amounts of algae block light from reaching the plants below.
3) eventually the plants die because they’re unable to photosynthesise enough.
4) bacteria feed on the dead plant matter. The increased number of bacteria decreases the oxygen concentration.
5) fish and other aquatic animal die.
