Unit 8: Topic 2 - Energy Flow Through Ecosystems

ecosystem

ecosystem

• the sum of all the organisms living in a given area and the abiotic factors they interact with

biotic factors

• living, or once living, components of an environment

abiotic factors

• nonliving (physical and chemical properties of the environment)

1st law of thermodynamics

energy can neither be created nor destroyed, only transferred

2nd law of thermodynamics

exchanges of energy increase the entropy of the universe

ecosystems and energy

• a net gain in energy results in energy storage or growth of an organism

• a net loss of energy results in loss of mass and eventual death of an organism

metabolic rate

• the total amount of energy an animal uses in a unit of time

  • can be measured in calories, heat loss, or by the amount of oxygen consumed (or CO2 produced)

    • oxygen is used in cellular respiration and CO2 is produced as a by-product

  • an animal’s _____ ________ is related to its body mass

    • smaller organisms = higher _______ ___

    • larger organisms = lower ____________

*****this is due to the surface area to volume ratio, a smaller animal has more body surface relative to its volume of metabolizing tissue, so more heat is lost

endotherms

• use thermal energy from metabolism to maintain body temperatures

ectotherms

• use external sources (i.e. sun/shade or other organisms) to regulate their body temperature

trophic levels

• species can be grouped based upon their main source of nutrition and energy

• energy CANNOT be recycled

  • the sun constantly supplies energy to ecosystems

primary producers

• tropic levels

• autotrophs

• use light energy to synthesize organic compounds

  • plants, algae, photosynthetic plankton

    • some organisms are chemosynthetic (produce food using energy created by chemical reactions

      • i.e. some bacteria and archaea organisms

heterotrophs

• trophic levels

• rely on autotrophs because they cannot make their own food

• primary consumers: herbivores

• secondary consumers: carnivores that eat herbivores

• tertiary consumers: carnivores that eat other carnivores

• decomposers: get energy from detritus (nonliving organic material; leaves, wood, dead organisms)

  • include fungi and many prokaryotes

  • important for recycling chemical elements

trophic structure

• determined by the feeding relationships between organisms

  • food chain: the transfer of food energy up the trophic levels

    • food web: linked food chains

primary production

• the amount of light energy that is converted to chemical energy

  • primary producers set a “spending limit” for the entire ecosystems energy budget

  • Gross primary production (GPP): total primary production in an ecosystem

  • Net primary production (NPP): the GPP minus the energy used by the primary producers for respiration (Ra)

secondary production

• the amount of chemical energy in a consumer’s food that is converted to new biomass

  • the transfer of energy between trophic levels is at around 10% efficiency

matter cycling

• unlike energy, matter cycles through ecosystems

  • matter is found in limited amounts, unlike solar energy

  • biogeochemical cycles: nutrient cycles that contain both biotic and abiotic factors

    • water, carbon, nitrogen, and phosphorus cycle

water cycle

• water is essential for all life and influences the rate of ecosystem processes

carbon cycle

• carbon is essential for life and required in the formation of organic compounds

nitrogen cycle

• nitrogen is important for the formation of amino acids, proteins, and nucleic acids

phosphorus cycle

• phosphorous is important for the formation of nucleic acids, phospholipids, and ATP (energy)