Energy in Ecosystems Flashcards
What is energy?
the capacity to work
What is the ultimate source of energy?
the sun
except for deep-sea hydrothermal ecosystems
What is PAR?
photosynthetically active radiation
only 60% of incident solar radiation is PAR
solar energy —-(photosynthesis)—-> chemical energy (adenosine triphosphate) —-> stored in plant tissue —> heat & mechanical energy during metabolic activities
What are the components of energy flow in an ecosystem?
sun -
~34% sunlight reflected off Earth’s atmosphere (dust & cloud)
~10% held by ozone layer, h20 vapour + gases
~56% reaches Earth’s surface
~2-10% used by plants
remaining absorbed as heat by water or ground
energy absorbed by plants and animals transform into heat
What is the photosynthesis formula?
CO2 + H2O + light ——–> C6H12O6 (chem. energy) + O2
How is chemical energy (C6H12O6) stored?
chemical energy is converted into biomass
stored energy in biomass is passed on as consumers feed
What is biomass?
is the total dry mass of organisms within an area or volume
What are ecological energetics?
include energy transformation which occur within the ecosystems
What is considered in regards to ecological energetics?
- QUANTITY of ENERGY REACHING and ecosystem per UNIT AREA per UNIT TIME
- QUANTITY of ENERGY TRAPPED by green plants & CONVERTED to a CHEMICAL FORM
- QUANTITY & PATH of ENERGY FLOW from green PLANTS to ORGANISMS of different TROPHIC LEVELS over a PERIOD OF TIME in a KNOWN AREA
What are the 2 laws concerning energy transformation in ecosystems?
explained by laws of thermodynamics:
- Energy may be TRANSFORMED from 1 form to another but it can NEITHER BE CREATED / DESTROYED
- processes involving energy transformation DOES NOT occur SPONTANEOUSLY, UNLESS there is DEGRADATION of ENERGY from a NON-RADOM TO A RANDOM FORM
(energy in living organisms = non-random i.e. chemical bonds
BUT when decomposition occurs = converted to random form by simpler form)
How is energy stored and transferred?
energy is stored in organic molecules (i.e. carbohydrates & lipids) can be transferred by cell respiration to ATP
How does ATP support cells’ metabolism?
What is ATP?
THE ENERGY CURRENCY OF THE CELL
building and breaking down of molecules (anabolism & catabolism)
Homeostasis
growth
How do inefficiencies occur in the transfer of energy btw organisms?
excretion - toxic organic molecules
digestion - some ingested materials not absorbed
uneaten remains
How are organisms interconnected?
connected in intricate manner as energy flow through those connections
depicted as food chains & food webs
What is the basic difference btw energy & nutrient flow?
energy = UNIDIRECTIONAL in food chains/webs
nutrients = cycled through food chain/web
What makes a food chain?
linear sequence
starts wt producer
2-5 organisms
arrow = is eaten by (show energy flow)
What makes a food web?
a series of food chains that are interconnected at various trophic levels, so as to form a number of feeding connections amongst different organisms of a biotic community
1 organism my occupy >1 trophic level
What is cellular respiration and its formula?
is the conversion of chemical energy into a form usable for cells
C6H12O6 + O2 ——–> CO2 + H2O + ATP
releases heat when organic compounds converted to ATP
What is the 10% law?
introduced by Raymond Lindeman
during the transfer of energy from organic food (consumption of biomass) from 1 trophic level to the next (energy transfer), only 10% of the energy from organic matter is stored as flesh
remaining is lost during transfer, broken down in respiration, lost to incomplete digestion, excreted
What is a trophic level?
the position of the organism in a food chain according to there feeding relationships with other organisms. Therefore organisms occupy specific place in food chain AKA trophic level
organisms on each trophic level depend on those at the lower trophic levels for their energy demands
What is a standing crop?
each trophic level has a certain mass of living material at a particular time AKA standing crop
measured as the biomass of an organism or their number in a unit area
What is a pyramid of energy?
any calculations of energy content, biomass or numbers has to include all organisms at that trophic level
SHOW FLOW OF EBERY btw TROPHIC LEVELS
measured in: units of energy / unit area / unit time
kJ m^-2 y^-1
How do I draw a pyramid of energy?
producer at bottom
each new level should be 1/10 of the previous level
get smaller as go up
kJ m^-2 y^-1
Why are food chains & biomass limited by energy loss btw trophic levels?
bc there is not much energy available at higher trophic levels due to 10% law
therefore, there are fewer apex predators when compared to producers
Outline how energy is passed through ecosystems
sun = initial source of energy for most ecosystems
producers = capture sun energy in photosynthesis
therefore, light energy —> chemical energy
energy passed from producer to consumer through feeding
energy transfer btw trophic levels inefficient due to 10% law
therefore, energy lost as heat/materials not eaten/ waste/ not assimilated
organisms cannot convert heat energy into other forms
food chains & biomass limited by energy availability
Explain the flow of nutrients & energy through ecosystems?
energy:
enters from sunlight
autotrophs capture light
energy transfer through trophic levels
energy loss
energy passes to decomposers (detritivores & saprotrophs) in dead organic matter
heat energy lost in cellular respiration
nutrients:
cycles / recycled
enter ecosystem through weathering rocks
recycles from decomposition of dead organisms
nutrients move through food chain by digestion
nutrients absorbed by producers
nutrients lost by leaching / sedimentation
