Ecosystem Energetics Flashcards
What is the basis of a natural ecosystem?
the energy source
Aside from being involved in nutrient cycling themselves, what makes bacteria so critical in energy transformation?
mitochondria and chloroplasts (organelles in eukaryotic organisms involved in energy transformation) evolved from bacteria
What are the major sources of energy for an ecosystem?
sunlight in the form of photons
or
some organisms can intake energy from geothermal or hydrothermal environments (not light related)
What other type of energy can photons be converted into?
heat
chemical energy (ATP)
What effect does the transformation of photons into heat energy have?
the heat energy warms the surface of the earth and the oceans
it drives the water cycle
it causes the wind and water currents
What governs the flow of energy in ecosystems?
the laws of thermodynamics
What is potential energy?
energy that is stored and available for and capable of doing work
ex. the ball at the top of a hill has stored energy
ex. potential energy stored in chemical bonds is released when wood burns
What is kinetic energy?
the energy of motion
it does work and acts as a force on an object to displace it
ex. the energy acting on the ball as it rolls down the hill
ex. kinetic energy is produced as heat and light as wood burns
What is the first law of thermodynamics?
energy is conserved
ie., it is not created or destroyed
it can change from one form to another
move from one place to another
it can act on matter in multiple ways
but there is never a gain or loss in total energy
What is the second law of thermodynamics?
when energy is transferred, entropy (disorder) increases and it’s in a form that can’t do work (loses capacity)
What happens to energy when it is transferred from one organism to another?
some energy will be stored in living tissues
some energy will be lost as heat
entropy will increase
If entropy increases with energy transfer, according to the second law of thermodynamics, how do ecosystems maintain order and energy?
ecosystems are open systems, which the second law of thermodynamics doesn’t apply to
the law only applies to systems within which no energy or matter is exchanged with the environment
the constant input of energy (mainly sunlight) in ecological systems contradicts the effects of entropy and maintains order and conserves energy
What is primary production?
the energy that is fixed in the system during photosynthesis
the rate at which autotrophs transform CO2 from the atmosphere or water into organic compounds
What are the 2 types of autotrophs?
chemoautotrophs
photoautotrophs
What are chemoautotrophs? give an example
primary producers that fix CO2 from their environment using energy from chemical compounds (oxidation of electron-donating molecules)
ex. Nitrosomonas europea use ATP to fix CO2
ex. Thiobacillus hydrothermalis use sulphur
What are photoautotrophs? give an example
primary producers that fix CO2 from their environment using energy from sunlight
ex. trees, herbs, mosses, Lamprocystis purpurea, Gammaproteobacteria, Cyanobacteria, Chloroflexus
What are the 2 measurements of primary productivity in a natural system?
gross primary productivity (GPP)
net primary productivity (NPP)
what is GPP?
Gross Primary Productivity is the TOTAL rate of photosynthesis by autotrophs
this includes energy converted for the organism’s own respiration
What is NPP? what is it’s formula?
Net Primary Productivity is the rate of energy storage in the form of organic molecules AFTER energy is used for cellular respiration (loss of energy)
NPP = GPP - Respiration
units: kcal/m^2/yr or g/m^2/yr
can be calculated from the Standing Crop Biomass accumulation
What is the standing crop biomass accumulation?
scientist makes multiple transects at different elevations and measures the diameter at breast height of the 4 closest trees to the transect as well as notes down the identification
How is NPP measured in aquatic systems?
the light/dark bottle method
Explain the light/dark bottle method that’s used to measure NPP in aquatic systems
used to measure the production and consumption of oxygen
light bottles are used to estimate NPP: they contain an incubated water sample with autotrophs - if photosynthesis surpasses respiration, dissolved oxygen will accumulate
dark bottles are used to estimate respiration: they contain the same sample incubated for the same time - if there’s no photosynthesis, and only respiration, the dissolved oxygen should decline
How can the light/dark bottle method be used to determine the amount of dissolved oxygen produced by photosynthesis?
the light bottle will have both photosynthesis and respiration occurring, whereas the dark bottle will only have respiration
to get the total amount of O2 that was produced by photosynthesis (GPP), you have to subtract the amount of O2 consumed by respiration (the purpose of the dark bottle)
What is the purpose of the dark bottle?
To learn how much O2 is consumed during respiration so it can be subtracted from the value found in the light bottle to determine the amount of O2 produced by photosynthesis
the dark bottle is the control