AP Bio Unit 8 Topic 2

• 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
• law of conservation of mass: chemical elements are continually recycled in the environment
• 2nd law of thermodynamics: exchange of energy increases the entropy of the universe
• a net gain in energy results in: energy storage or growth of an organism
• a new 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
• metabolic rate 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 metabolic rate is related to its body mass

  • smaller organisms: higher metabolic rate
  • larger organisms: lower metabolic rate
• organisms use different strategies to regulate body temperature
• endotherms: regulation strategy that uses thermal energy to maintain body temperatures
• ectotherms: strategy that uses external sources (ie sun/shade or other organisms) to regulate their body temperature
• species can be grouped into trophic levels based upon their main source of: nutrition and energy
• unlike mass, energy cannot be recycled
• the sun constantly supplies energy to ecosystems
• primary producers (autotrophs) use light energy to synthesize organic compounds

  • plants, algae, photosynthetic plankton
• some organisms are chemosynthetic (vs photosynthetic) meaning they produce food using the energy created by chemical reactions
• heterotrophs: 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 (secondary)
• decomposers: get energy from detritus (nonliving organic materials; leaves, wood, dead organisms)
• decomposers include fungi and many prokaryotes, and are important for recycling chemical elements
• the trophic structures of a community are determined by the feeding relationships between organisms
• food chain: the transfer of food energy up the trophic levels
• food webs: linked food chains
• any changes to the availability of energy can disrupt ecosystems
• if energy resources change, so can the number and size of trophic levels (increase energy, increase trophic levels/size; decrease energy, decrease trophic levels/size)
• a change at the producer level can affect the number and size of the remaining trophic levels
• 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)
• satellite images show that different ecosystems have varying NPP
• the amount of energy in a consumer's food that is converted to new biomes
• the transfer of energy between trophic levels is at around 10% efficiency
• unlike energy, matter cycles through ecosystems