Matter Cycles, Energy Flows

energy & nutrients

energy &

Life driven by complementary reactions


energy invested, stored in glucose

energy harvested for cell work

• Matter is recycled

• Energy, however, must be continually input


    • Photosynthesis is the transformation of radiant energy into chemical energy, via the chemical change of inorganic molecules into sugars performed by photoautotrophes
      • Sunlight is the main energy for life

    • Chemoautotrophes rely on energy stored in chemical bonds of inorganic compounds (H2S) found at hydrothermal vents in the deep ocean


Herbivores (primary consumers; prey) eat producers…

…in turn are eaten by carnivores/ominvores (secondary, tertiary consumers)..

…dead-ending at top consumers, often apex predators

energy & matter transferred

energy & matter transferred

energy & matter transferred

Relationships mapped as Food Web

Arrows indicate direction of energy transfer

Energy transfer is inefficient

• transformed into heat entropy!

• locked in waste to decomposition food web

• used in respiration

• used for growth aka biomass, transferred in food web



  • consumers that derive energy from organic waste and dead organisms
  • Bacteria, insects ,fungi
  • aka decomposers

Pyramid Power

Shape reflects trophic (feeding) levels

Greek: trophos = nutrition

Pyramid shape reflects energy use & transfer

Only 10% is transferred on average

Most energy is transformed (‘lost’) into heat

Pyramid shape reflects number of organisms

Many producers needed to support a smaller number of consumers

Pyramid shape reflects relative biomass

Large base supports smaller (less productive) trophic levels


  • Along with nutrients & energy, chemicals are ingested that are not broken down or easily excreted
      • pollutants, heavy metals, pesticides
  • Passed between the links of a food web
  • These chemicals – usually not water soluble - accumulate in tissues

Food webs also transfer contaminants

Organisms higher in the web have more opportunities to ingest the toxin, increasing concentration in their tissues






It’s exponential

Greatest quantity of toxin per individual is in those top consumers





The pyramid is inverted

• In humans, Hg causes brain damage, death

Ex: Mercury concentrates in fish

• Limit your tuna intake!

Albacore 1x/2weeks

Chunk light 1x/week

Source: EPA/FDA


Weakens bird egg shells

Linked to cancer

Also immune, reproductive, neurologic, endocrine


Ex: PCB’s from electrical, plastics industries


between biotic, abiotic reservoirs

water cycle



from bodies of water

• Condensation

into clouds, fog

• Precipitation

as rain, snow…

Yada yada yada

What about the BIOTIC?

• Water, H, & O atoms needed by, stored in, and moved through organisms as part of the water cycle

ex: used in photosynthesis, produced in respiration,

transpired in great quantities by plants




• Vast stores of C in

atmosphere, oceans as CO2, in earth as fossil fuels

• Taken up by plants in photosynthesis

• Stored as organic molecules in tissues of organisms

• Organic molecules used by organisms in fermentation, respiration

• C released as CO2 into atmosphere, oceans

Plants do it Fungi do it………………..Even these guys do it

• Also taken up by aquatic

animals for shell building


nitrogen cycle

N2 is abundant in atmosphere

a form not usable by most organisms

• Solution? Converted by bacteria in root nodules of legumes (peas, beans)

N-fixation N2 -> NH3

• Further converted to nitrites & nitrates by soil bacteria nitrification NH3 -> Nox

• NOx taken up by plants, used to build proteins, DNA

• Decomposition also produces NH3


• Other bacteria convert NOx in soil to atmospheric N2


phosphorous cycle

• Largest reservoir is on land in rocks, soil minerals and ocean sediment

no atmospheric source

• As rock weathers, phosphate slowly released to soil

low availability limits plant growth

needed to build proteins, DNA

• Erodes with soil into rivers, lakes and oceans, settles to floor

• Therefore a SLOW cycle

PPTap - matter cycles energy flows - Google Slides