Energy and Ecosystems Flashcards
How do plants use the sugars from photosynthesis
-primarily as respiratory substrates
-to synthesis other biological molecules e.g. cellulose
biomass
total dry mass of tissue or mass of carbon measured over a given time in a specific area.
the units of biomass
when an area is sampled: gm^-2
when a volume is being sampled: gm^-3
how can the chemical energy stored in dry biomass be estimated
using calorimetry
energy released= specific heat capacity of water x volume of water (cm3) x temperature increase of water
why is bomb calorimetry preferable to simple calorimetry
reduces heat loss to surroundings
how could a student ensure that all water had been removed from a sample before weighing
heat the sample and reweigh it until the mass reading is constant
Gross Primary Production (GPP)
the total chemical energy store in a plant biomass, in a given area or volume
Net Primary Production (NPP)
the chemical energy available for plant growth, plant reproduction and energy transfer to other trophic levels after respiratory losses to the environment have been taken into account.
NPP equation
NPP = GPP - R
where R represents respiratory losses.
Why is most of the Sun’s energy not converted to organic matter?
-most solar energy is absorbed by atmosphere or reflected by clouds
-photosynthetic pigments cannot absorb some wavelengths of light
-not all light falls directly on a chlorophyll molecule
-energy lost as heat during respiration/photosynthesis
net production of consumers
N = I - (F + R)
I: chemical energy from ingested food
F: energy lost as faeces and urine
R: respiratory losses
saprobiants/decomposers
group of organisms that break down complex matter in dead organisms into simple matter.
they release valuable minerals and elements in this recycling.
why does biomass decrease along a food chain
energy lost in faeces and nitrogneous waste (urine).
some of the energy is not consumed.
energy lost to surroundings as heat.
primary and secondary productivity
rate of primary or secondary production
biomass in a specific area over a given time frame
common farming techniques used to increase efficiency of energy transfer
-exclusion of predators-no energy lost to other organisms in food web.
-artificial heating-reduce energy lost to maintain constant body temperature.
-restriction of movement
-feeding is controlled at the optimum.
