Energy Transfer + Productivity Flashcards
Why is most of the sun’s energy not converted to organic matter by photosynthesis? (4pts)
1) Over 90% of the Sun’s energy is reflected back into space by clouds and dust or absorbed by the atmosphere
2) Not all wavelengths of light can be absorbed and used for photosynthesis
3) Light may not fall on a chlorophyll molecule
4) A factor that may limit the rate of photosynthesis, like low carbon dioxide levels
What is the gross primary production (GPP)?
The total quantity of the chemical energy store in plant biomass, in a given area or volume, in a given time
What is the net primary productivity (NPP)?
The chemical energy store which is left when the losses of respiration have been taken into account
What is the equation to calculate the net primary productivity (NPP)?
Net Primary Productivity (NPP) = Gross Primary Productivity (GPP) - Respiratory losses (R)
What is the percentage of net primary production that primary consumers can use from plants for growth?
Usually less than 10% of the net primary production in plants can be used by primary consumers for growth
What is the percentage of net primary production that secondary and tertiary consumers use from their prey?
Secondary and tertiary consumers transfer up to 20% of the energy available from their prey into their own bodies.
Why is there low percentages of energy transferred at each trophic level?
(4pts)
1* Some of the organism has not been consumed
2* Some parts are consumed but cannot be digested, and as a result are lost in the faeces
3* Some of the energy is lost in excretory materials, urine
4* Some energy losses occur as heat from respiration, which is lost to the environment
What is the equation to calculate the net production of consumers?
N = I - (F + R)
This equation: N = I - (F + R)
What does each letter stand for?
N = net production
I = the chemical energy store of ingested food
F = the energy lost in faeces and urine
R = the energy lost in respiration
What does the relative inefficiency of energy transfer between trophic levels explain? (3pts)
1* Most food chains have only four or five trophic level because insufficient energy is available to support a large enough breeding population at trophic levels higher than these
2* The total mass of organisms in a particular place (biomass) is less at higher trophic levels
3* The total amount of energy available is les at each level as one moves up a food chain
What does the productivity of an ecosystem depend on?
The productivity of an ecosystem depends on the abiotic and biotic factors
What causes the rates of photosynthesis to be maximised?
An abundance of abiotic factors and biotic factors will maximise the rates of photosynthesis
How do you calculate percentage efficiency?
(Energy available after the transfer ÷ energy available before the transfer) x 100
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