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6) Ecosystems 1: Energy Flow
Terms in this set (15)
describe the movement of energy thru an ecosystem
energy flows thru an ecosystem
photosynthesis, light energy, cellular respiration, heat energy
energy= a common currency for all organisms, need a constant input of energy to stay alive
moves in one direction
all life undergoes cellular respiration- some energy released as heat
whenever organisms use light or chemical bond energy some of it is converted to heat - can't be converted to other forms of energy
definition of an ecosystem
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows.
describe the different tropic levels of ecosystems
tertiary, secondary, primary, producer:
autotroph, makes own food, photosynthesis
herbivore, animals that eat the autotrophs
ex) rabbit that eats grass
animals that eat herbivores
ex) snake that eats rabbits
a carnivore that feeds on other carnivores (an animal that feeds only on secondary consumers)
eat plants and animals
detritivores and decomposers
get nutrients from detritus
why are chain lengths short in most food webs
the energetic hypothesis: suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain. Only about 10% of the energy stored in the organic matter of each trophic level is converted to organic matter at the next trophic level.
-energy produced along the chain is inefficient- limiting chain length
-energy is less and less as you move up levels
secondary production vs primary production
autotrophs undergo photosynthesis:
gross primary production= amount of light energy converted to chemical energy
secondary production in primary consumers: new biomass (energy available to next trophic level)
Primary productivity is the rate at which energy is converted by photosynthetic and chemosynthetic autotrophs to organic substances. The total amount of productivity in a region or system is gross primary productivity.
Secondary production is the generation of biomass of heterotrophic (consumer) organisms in a system. This is driven by the transfer of organic material between trophic levels, and represents the quantity of new tissue created through the use of assimilated food.
why is secondary production smaller than primary production
ex) bird that eats caterpillar only gets a fraction of chemical energy that was initially available in the leaf!
consider the implications of energy flow on the human population
Amount of energy available to top level consumers is small compared to that available to lower level consumers
few top-level consumers
Top-level consumers require lots of territory
Many predators highly susceptible to extinction
relevant to human pop:
A person obtains far more calories by eating grains
directly as a primary consumer than by eating the same
amount of grain fed to an animal.
Worldwide agriculture could effectively feed more
people and require less land if we all fed more
efficiently. Estimates of K depend partly on our diet.
explain the fate of fat-soluble chemicals as they move up a food chain
biomagnification- the increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain
ex) DDT (insecticide) becomes concentrated in the tissues of organisms as you move up the food chain (ex birds of prey)
- DDT led the decline of these birds because the DD would get concentrated in their fat tissue and make their egg shells crack
describe the basic carbon cycle
Plants use carbon dioxide and sunlight to make their own food and grow. The carbon becomes part of the plant. Plants that die and are buried may turn into fossil fuels made of carbon like coal and oil over millions of years. When humans burn fossil fuels, most of the carbon quickly enters the atmosphere as carbon dioxide.
Carbon dioxide is a greenhouse gas and traps heat in the atmosphere. CO2 levels are increasing globally
THIS SET IS OFTEN IN FOLDERS WITH...
1) Descent with Modification
2) Mechanisms of Evolution
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