Chapter 20 Flashcards
Define potential energy
Stored energy that is available/capable of performing work
Define kinetic energy
Energy of motion. Energy that is currently performing work
What is the first law of thermodynamics?
Conservation of energy - energy is neither created nor destroyed
What is the 2nd law of thermodynamics?
Energy transfers - When energy is transferred, entropy increases
Define entropy
The idea of chaos in a system. The state of disorder, randomness or uncertainty.
CANNOT do work.
What is an example of entropy?
- Energy being transferred from one organism to another as food. Some energy is stored in tissue, some is lost as heat. Since the energy lost as heat cannot perform any more work, entropy/chaos increases.
Define primary productivity
Rate at which autotrophs convert CO2 into organic compounds
(inorganic -> biomass)
What is a chemoautotroph?
Autotroph that converts CO2 into organic compounds through chemical compounds
What is a photoautotroph?
Autotroph that converts CO2 into organic compounds through sunlight.
What is GPP
Gross Primary Productivity. Total rate of photosynthesis by autotrophs
What is NPP
Net Primary Productivity. The rate of energy from organic molecules being stored after energy is expended from cellular respiration
How is Rate of Production expressed?
kcal/m^2/yr
Units of energy / Unit area / Unit of time
What regulates secondary productivity?
Primary productivity
What 3 things affect terrestrial primary productivity?
Precipitation
Temperature
Nitrogen Availability
What is the relationship between NPP and length of growing season?
The longer the growing season, the increase of net productivity.
What is the relationship between PAR and water depth?
PAR declines exponentially with increase in water depth.
What is PAR?
Photosynthetically active radiation. Essentially wavelengths that autotrophs can photosynthesize.
Where is photosynthetic rate and GPP highest in relation to PAR?
Highest at intermediate levels of PAR.
What is compensation depth?
When GPP = R (respiration rate). This means that NPP = 0.
In aquatic systems specifically, what are limiting factors for NPP and why?
Nutrients (nitrogen, phosphorus, iron)
due to nutrients from deeper ocean waters needing to be transported to surface waters for photosynthesis.
What 3 things did nutrient enrichment experiments teach us:
- Nitrogen addition stimulates phytoplankton the most
- Iron follows closely in stimulating growth
- Phosphorus addition did not really stimulate growth.
What does Iron do?
Is a cofactor of most enzymes. Allows for correct folding of proteins — specifically nitrogenase.
What are limiting factors for NPP in stream ecosystems?
light and nutrient availability.
Canopy cover above the stream affects light availability.
What is an autochthonous carbon
Carbon produced within an aquatic ecosystem.
Comes from photosynthesis by plants, algae, and phytoplankton
What is an allochthonous carbon
Carbon produces outside an aquatic ecosystem. Comes from dead organic matter from adjacent terrestrial ecosystems
Can be DOM or POM
What is DOM? POM?
Dissolved organic matter (DOM)
Particulate organic matter (POM)
What is the river continuum concept?
Continuum along a flowing body of water of the importance of allochthonous and autochthonous carbon sources.
Small streams will have a majority of ____________ carbon due to _____________.
Allochthonous carbon due to canopy cover.
As streams increase in size, relative abundance of allochthonous carbon _____ while autochthonous carbon _____ due to a ______ in canopy cover.
decreases, increases, decrease
How does NPP change in later stages of succession?
Plant focus turns to growing stems and branches instead of leaves. This results in an increase in biomass, but constant productivity of the plant.
This decreases NPP compared to biomass.
A system with high allochthonous carbon has an increased number of ________?
decomposers
A system with high autochthonous carbon has an increased number of ________?
filter feeders
What is secondary production?
AKA secondary productivity.
Net energy allocated to production…… formation of living heterotroph biomass over a period of time
Heterotroph biomass is equal to…
autotroph NPP (grams/area/time)
When is secondary production the greatest?
When the birthrate of the population and the growth rate of individuals is the highest.
What is “The World is Green” proposition?
Plant biomass accumulates because predators keep the herbivore population in check. (top-down control!)
What is trophic cascade? What is it caused by?
Changes in the population at the top of the food chain trigger a chain reaction that affects species at lower levels. Top-down control.
Food ingested by a consumer can be either (2 things):
Assimilated in the gut (A)
OR
Expelled from the body as waste (W)
Food assimilated in the gut can then be used during (2 things):
Respiration (R) - body maintenance
Production (P) - growth, development, reproduction
What is Assimilation Efficiency?
A / I —- measures the efficiency of extracting energy from food
I = consumer
What is Production Efficiency?
P / I —– measures how efficiently assimilated energy is incorporated into secondary production.
What is detritus?
Organic material derived from dead/decaying organisms
(Fallen leaves, animal carcass, etc.)