Energy transfer in ecosystems Flashcards
What is an ecosystem?
All of the living organisms in a particular area and all of the abiotic conditions
What is biomass?
The mass of living material in an organism
How is energy transferred through an ecosystem?
When one organism eats another organisms
Why is dry mass measured rather than wet mass?
The water content of living tissue varies
How is mass dried?
Dried in an oven set a low temperature
Weighed at regular intervals until the mass remains constant - all water removed
What are typical units for dry mass?
kg m-2
What are typical units for biomass?
kg m-2 yr-1
What is used to measure the amount of chemical energy stored in biomass?
Calorimetry
How does calorimetry work?
A sample of dry biomass is burnt and the energy released is used to heat a known volume of water, the change in temperature is used to calculate energy
In calorimetry, what is the amount of energy released measured in?
Joules or kilojoules
How do you get from kilojoules to joules?
x 1000
What is Gross primary production (GPP)?
The total amount of chemical energy converted from light energy by plants, in a given area, at a given time
What is the NPP?
The energy available to the plant for growth and reproduction, stored in the plant’s biomass, and the energy available at the next stage in the food chain
What is the equation for NPP?
NPP = GPP - R
Why is photosynthesis not 100% effective?
Not all light energy absorbed by a plant will be converted to chemical energy
How much of the energy is lost and not transferred to the next trophic level?
90%
How is energy lost in food chains?
Not all food is eaten
Some parts are indigestible
Some lost to environment through respiration and excretion
What is a consumers net production?
The energy thats left after all loses stored in the consumers’ biomass and is available to the next trophic level
Whta is the equation for the consumers net production ?
N = I - ( F+R )
What does each part of the equation for the consumers net production stand for?
N = net production I = Chemical energy in ingested food F = Chemical energy lost in faeces and urine R = energy lost through respiration
How do you calculate the efficiency of energy transfer?
% efficiency of energy transfer =
net production of trophic level
——————————————– x100
net production of previous trophic level
