energy through ecosystems 3.5 Flashcards
(19 cards)
how do plants use the sugars from photosynthesis (2)
primarily as respiratory substrates
to synthesise other biological molecules
eg cellulose
define biomass
total dry mass of tissue
or mass of carbon
measured over a given time in a specific area
units for biomass
area gm-2
volume gm-3
how can the chemical energy store in dry biomass be estimated
using calorimetry
energy released equation
(for calorimetry)
energy released = specific heat capacity of water x volume of water x temperature increase of water
why is bomb calorimetry preferable to simple calorimetry
reduces heat loss to surroundings
how to ensure all water has been removed from sample before weighing
heat the sample and reweigh it until the mass reading is constant
define gross primary production (GPP)
total chemical energy
in plant biomass
within a given volume or area
define net primary productivity (NPP)
total chemical energy available for
plant growth, plant reproduction and energy transfer to other trophic levels
after respiratory losses
mathematical relationship between GPP and NPP
NPP = GPP - R
R represents respiratory losses
why is most of the suns energy not converted to organic matter (4)
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
how can the net production of consumers be calculated
N = I - (F + R)
I = chemical energy from ingested food
F = energy lost as faeces and urine
R = respiratory losses
why does biomass decrease along a food chain (3)
energy lost in nitrogenous waste (urine) and faeces
some of the organism is not consumed
energy lost to surroundings as heat
define primary and secondary productivity
rate of primary or secondary production
biomass in a specific area over a given time period
outline some common farming practices used to increase the efficiency of energy transfer (4)
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
equation for % efficiency
energy converted to a useful form (J) x 100 / total energy supplied (J)
explain why the length of food chains is limited
energy lost at each trophic level
so there is insufficient energy to support a higher trophic level
what is a pyramid of biomass
diagram that shows the biomass at each trophic level
why is a pyramid of biomass preferable to a pyramid of numbers
shape of pyramid of numbers may be skewed since a small number of producers can support many consumers
