lecture 18: energy and nutrient Flashcards
(29 cards)
What is an ecosystem?
all interacting biotic (living) and abiotic (nonliving) components of a system functioning together.
What are the key ecosystem functions?
Transfer and cycling of energy and nutrients.
What is the main energy source for ecosystems?
sun
How does energy enter and leave an ecosystem?
Enters as sunlight, exits as heat.
Are ecosystems open or closed systems?
Open—constant energy input and output.
What does the First & 2nd Law of Thermodynamics state?
Energy cannot be created or destroyed.
Energy becomes less available with each transfer (some lost as heat).
What is primary production?
The rate at which plants convert sunlight into organic matter.
What affects primary production?
Abiotic factors like light, water, nutrients, temperature.
What is secondary production?
Energy transformed by consumers into growth and offspring.
What is production efficiency (P/A)?
the proportion of assimilated (taken in) energy used for growth and reproduction.
What general pattern is seen in P/A?
Invertebrates > vertebrates; ectotherms > endotherms; (because endo uses to heat their body)
carnivores > herbivores.
What is trophic efficiency?
Pn+1/Pn – energy available to the next trophic level.
What is the 10% rule?
Only ~10% of energy is passed to the next trophic level. 2nd law
Heterotrophs: What are the two types of food chains?
Grazing (living tissue) and Detrital (dead tissue/waste).
Which food chain dominates in most ecosystems?
Detrital food chain.
What is internal cycling?
Recycling of nutrients within an ecosystem by decomposers.
What is mineralization?
Conversion of organic compounds into inorganic nutrients.
what two processes control nutrient cycling?
Primary production (inorganic → organic) and decomposition (organic → inorganic).
How does the ecosystem nutrient cycle form a feedback loop?
1° production determines dead matter → fuels decomposition → recycles nutrients → supports new 1° production.
What is a biogeochemical cycle?
The movement of nutrients between living and nonliving components in a cyclic path.
What abiotic process adds nutrients to ecosystems?
Weathering of rocks and minerals.
What is the main source of carbon for organisms?
CO₂ from the atmosphere.
What releases CO₂ back into the atmosphere?
Respiration by plants, animals, and decomposers.
Where is long-term carbon stored?
In peat, humus, and fossil fuels (oil, coal, gas).
