Energy And Ecosystems Flashcards
Gross primary production
The total amount of energy made by producers per unit area per unit time
Total quantity of chemical energy stored in plant biomass, in a given area or volume, in a given time
Respiratory loss
The energy used by organisms for respiration
(Active transport, movement/ muscle contraction, heat)
Net primary production
The amount of chemical energy a producer stored as biomass per unit area per unit time (after respiratory losses to the environment have been taken into account)
The energy available to the next trophic level
I
R+F+N
Total energy ingested by consumer (chemical energy store in ingested food)
Energy transfer efficiency
N/I x100
Population
All the organisms of a single species that occupy the same habitat at the same time
Community
All the organisms of all the species in a habitat/ an ecosystem at a given time
Habitat
Place where an organism lives
Niche
Role of a species in an ecosystem
Trophic level
Each stage of the food chain
Ecosystem
Abiotic and biotic factors interchanging with each other in a dynamic equilibrium
The abundance and distribution of organisms are controlled by biotic and abiotic factors
A biological community of interacting organisms and their physical environment
Productivity
How much energy is transferred from one trophic level to the next
Rate of primary or secondary production (biomass in a given area in a given time)
Why is energy transfer efficiency low from sun to producer
Wrong wavelength (not all wavelengths can be absorbed and used for photosynthesis)
Light strikes non photosynthetic region
Light reflected back into space by clouds and dust, or is absorbed by the atmosphere
Lost as heat
A factor such as low carbon dioxide levels may limit rate of photosynthesis
Why is energy transfer efficiency low from producer to primary consumer
Respiratory loss (plant uses energy for metabolic processes)
Lost as heat
Not all the plant is eaten
Some food isn’t digested
Why is energy transfer efficiency low from primary to secondary consumer
Respiratory loss (primary consumer uses energy for metabolic processes)
Lost as heat due to respiration (maintaining body temperature)
Not all the animal is eaten
Some of the food isn’t digested
Lost as excretory material (urine)
Causes of energy transfer efficiency being especially low
Old animal (stopped growing so less energy goes to biomass)
Herbivores (more faeces)
Homiotherms and endotherms (warm blooded) as increased metabolism to keep warm
Increasing energy transfer efficiency, plants
Shorten food web
Use fertilisers
Shortening the food web
Reduces competition so the plant has more energy to make biomass
Herbicides (kill weeds), fungicides (reduce fungal infections), insecticide (chemical control of pests), biological controls (natural predators of pests)
Fertilisers
Prevent growth being limited by lack of nutrients
Nitrates
Increasing energy transfer efficiency, animals/ livestock
Reduce respiratory loss
Slaughter animal while still growing (more energy being made into biomass)
Keep predators away
Control diet (higher percentage of food digested, less faeces)
Reducing respiratory loss
Restrict movement so less respiration so more energy goes to making biomass
Keep warm in winter so less respiration
Way of increasing energy transfer efficiency both plants and animals
Artificially select organisms with a high yield
NPP equation
Chemical energy stored in ingested food (I)- (energy lost in faeces and urine (F) + energy lost in respiration (R)
Producer
An organism that synthesises organic molecules from simple organic ones (CO2 and H2O)
Most are photosynthetic
Saprobiont
An organism that obtains its food from the dead or decaying remains of other organisms
Consumer
An organism that obtains energy by eating another
Biomass
Total mass of living material in a specific material at a given time
Why is measuring biomass unreliable
Volume of water in living organisms varies
Measure mass of carbon or dry mass instead
Problems with measuring dry mass
Organisms have to be dead so only small samples can be measured so not representative
Calculating biomass from dry mass
Sample of biomass warmed on a scale until the mass remains constant meaning all water has evaporated
Temperature must be low to avoid combustion
Kgm-2
Calorimetry to calculate biomass
Burn a sample of biomass completely
Heat a known mass of water
Measure temperature change of water
Calculate energy released
Percentage efficiency
Energy available after transfer/ energy available before transfer x100
Measuring biomass
Mass of carbon
Dry mass of tissue per given area (chemical energy store can be estimated using colorimetry)
Biomass definition
Total mass of living material in a specific area at a given time
Calculating NPP
GPP-R
