Energy Transfer Notes

Ecology: the scientific study of interactions among organisms and their physical environment

  • organisms are interdependent w/ each other and w/ the environment

6 Levels of Ecological Classification:

  1. Individual/Organisms

  2. Population: a group of organisms of the same species living in the same area at the same time

  3. Community: all the populations living together w/in an area —> all the biotic factors in an area

  4. Ecosystem: all the biotic + abiotic factors in an area

  5. Biome: a group of ecosystems that share similar climates and typical organisms

  6. Bioshpere: our entire planet, w/ all its organisms & physical environments

Biotic Factors: living/biological influences on an organisms

  • EX: predator, prey, food availability, etc.

Abiotic Factors: non-living influences on an organism

  • EX: soil, water, temperature, etc.

  • Abiotic + Biotic factors together, create the ecosystem

Why are ecosystems open systems?

  • bc energy & matter can leave an ecosystem naturally or due to human involvement

  • natural process would be migration of animals or seeds of plants traveling (by wind)

  • human involvement: import/export type stuff —> harvesting crops in one area and moving them somewhere else, planting new trees, etc.

Distinguish between open systems and closed systems:

  • open: energy AND matter can enter & exit

  • closed: only energy can enter & exit

    • EX: could be as small as a mesocosm or as large as a biosphere

  • sunlight is the principal source of energy that sustains most ecosystems

What process allows organisms to harness the energy in sunlight?

  • PHOTOSYNTHESIS

  • sunlight is the principal source of energy that sustains most ecosystems

Define these root words:

  • Auto: self

  • Hetero: other

  • Troph: nourishment

Autotroph: organisms that can produce their own organic molecules to then be broken down into ATP energy

  • another name for autotrophs is PRODUCERS

Photoautotrophs: organisms that use light energy to produce organic molecules

  • EX: plants, cyanobacteria, algae

Chemoautotrophs: organisms that obtain energy through the oxidation of inorganic compounds —> iron, sulfur, magnesium, etc.

  • EX: extremophiles (prokaryotes & protozoa) —> living near hydrothermal vents and in hot springs

Heterotrophs: organisms that CANNOT produce their own organic molecules —> they must be obtained from other organisms

  • another name for heterotrophs is CONSUMERS

  • BOTH heterotrophs & autotrophs HAVE TO be able to break down organic molecules into ATP —> RESPIRATION

Herbivore: animal that eats producers (plants)

  • EX: cow, deer, goats, caterpillars

Carnivore: animal that kills and eats other consumers

  • EX: lions, snakes, cats, giant river otters

Omnivore: animal whose natural diet includes plants AND other animals

  • EX: humans, bears, pigs

Scavenger: animal that consumes the carcasses of other animals that have been killed by predators or have died of other causes

  • EX: vultures, hyenas, condors

  • Herbivores, Carnivores, Omnivores, and Scavengers can all do internal digestion —> so they’re referred to as “CONSUMERS”

Describe the role of decomposers in an ecosystem:

Decomposers: break down dead organisms & organic matter —> they extract energy/nutrients from the decaying matter (feces, leaf litter, dead animals, etc.)

  • they are considered Heterotrophs, but NOT CONSUMERS

  • decomposers are a type of heterotroph

  • EX: bacteria, fungi, invertebrates

  • decomposers play a crucial role in the cycling of nutrients & matter

  • decomposition of organic matter returns monomers & nutrients to the soil —> makes it available for plants to reuse

Distinguish between saprotrophs and detritivores:

Saprotrophs: obtain organic nutrients from dead organisms through EXTERNAL DIGESTION

  • they secrete hydrolytic enzymes & break down molecules outside the organism, then the nutrients are absorbed

  • EX: fungi & bacteria

Detritivores: obtain nutrients from detritus using INTERNAL DIGESTION

  • Detritus: organic matter created during the decomposition of dead organisms

  • EX: earthworms, millipede, snails, etc.

What do arrows show in a food chain/food web?

  • arrows show the direction of the transfer of energy & biomass

Compare & Contrast food chains/food webs:

  • Food chains: show the flow of energy & biomass through a community

  • Food webs: several food chains that are interconnected

Why are decomposers rarely included in a food chain/web?

  • because it would be way too complex to include them

  • this is why food webs are a MORE COMPLETE description of energy transfer, but not fully complete

Describe what organisms use energy for once they make organic molecules (autotrophs) or consume other organisms (heterotrophs):

  • some is stored by the organism —> most is used for cellular respiration

  • CR produces ATP energy for the organism (to use to survive & do processes of life)

  • some of it is lost as heat —> dissipates into the environment

10% Rule:

  • only 10% of the available energy at a lower trophic level can be transferred to the next successive trophic level

Identify & Describe the 5 sources of energy loss in an ecosystem:

  1. Heat Dissipation: heat produced as a byproduct of metabolic reactions (including cellular respiration) —> this heat is lost to the environment

  2. Incomplete Consumption: organisms don’t fully eat all the biomass of their food; uneaten parts represent loss of energy

  3. Inefficient Digestion: not 100% of the nutrients/energy is absorbed from an organism’s food

  4. Use in Metabolic Processes: organisms will use the extracted energy from food to perform functions of life that require energy

  5. Inefficient Energy Conversion & Storage: not 100% of energy & nutrients are able to be stored w/in an organism

Explain why energy loss limits food chain length:

  • energy losses cause a great decrease in the amount of energy stored as biomass at each successive trophic level

  • as energy moves up the food chain, the amount of energy available eventually becomes insufficient to sustain an additional trophic level

Maximum Length of a food chain:

  • typically, 4-5 trophic levels long because there wouldn’t be enough energy available for higher levels

Define energy pyramid and state the types of units that you would find in an energy pyramid:

  • Energy pyramid: diagram to represent the amount of energy available at each trophic level

  • units used are energy units per area per time (kJ m^-2 year^-1)

Biomass: the total dry mass of a group of organisms in a specific area or volume

  • can be used to measure energy bc the tissues of organisms are composed of organic compounds which contain energy —> biomass inherently contains energy

  • indirect way to measure energy

  • more biomass = more energy available

Outline how biomass is related to energy:

  • biomass can be used to measure energy bc the tissues of organisms are composed of organic compounds which contain energy —> biomass inherently contains energy

Primary Productivity: rate at which producers accumulate carbon compounds in their biomass

  • AKA: how efficiently/quickly producers do photosynthesis & store organic compounds

  • when producers to photosynthesis, some of the organic compounds are broken down to be used for their own energy, so it’s not stored

  • the excess organic molecules that aren’t immediately broken down is stored in the form of biomass

  • biomass accumulates as organisms grow or reproduce

  • measured in units of mass per unit area per unit time —> such as g m^-2 yr^-1

State how producer biomass is related to ecosystem diversity

  • more producer biomass can support a greater number & diversity of consumers w/in an ecosystem

    • bc there’ll be more energy available at successive trophic levels

List 3 Factors that impact primary productivity: (things that impact photosynthesis)

  • Temperature

  • Precipitation

  • Nutrient availability in the soil

  • more sunlight, water, and nutrient-rich soils = more primary productivity

Describe how gross and net primary productivity are related to e/o

  • Gross Primary Productivity: total amount of energy captured as biomass by primary producers in an ecosystem

  • Net Primary Productivity: the energy available to consumers at higher trophic levels

  • NPP = GPP - R

    • R is loss of energy bc of respiration

    • 10% from the NPP can transfer to next level

Secondary Productivity: the rate at which consumers accumulate carbon compounds as part of their own biomass

  • Heterotrophs also experience a loss of biomass during cellular respiration

Describe how gross and net secondary productivity are related to e/o

  • Gross Secondary Productivity: total biomass assimilated by heterotrophs in an ecosystem

  • Net Secondary Productivity: the biomass that remains after accounting for respiratory losses

  • NSP = GSP - R

  • R is loss of energy due to respiration