Ch.20&21- Energy Flow

Question 0

Earth is an Open system for Energy

Answer 0

• Energy arrives from the sun

- Energy leaves by radiating into space

Question 1

Earth is a Closed system for matter

Answer 1

-Chemicals are converted, but are not gained or lost

Question 2

Primary prodcution

Answer 2

-all energy in an ecosystem comes from primary production (autotrophs)

Question 3

Gross primary production (GPP)

Answer 3

total amount of carbon fixed by autotrophs in a n ecosystem

-controlled by climate, nutrients, and autorophes biomass

Question 4

Net Primary production (NPP)

Answer 4

NPP= GPP-carbon lost to respiration

-plants need ~ 1/2 carbon fixed to support biosynthesis and cellular maintenance

Question 5

Actual evapotranspiration

Answer 5

AET= the total amount of water that evaporates and transpires off a landscapre (mL water/year)

Question 6

Trophic dynamics

Answer 6

-energy must be transferred from autotrophs to higher trophic levels
~in trophic pyramids, the amount of biomass or energy= size in the layer of pyramid
~size of layer determined by:
-amount of NPP
-Ecological efficiency

Question 7

Ecological efficiency

Answer 7

The percentage of energy at one trophic level transferred to another

Question 8

Consumption efficiency

Answer 8

-Proportion of available biomass that is ingested
-higher trophic levels=higher consumption efficiency
Ex: zebra eats grass, lion eats zebra

Question 9

Assimilation efficiency

Answer 9

-proportion of ingested food that is absorbed by digestive trac (determined by food quality)
-Higher food quality as you move up trophic levels
Ex: assimilation efficiency:
herbivores= 20-50%, carnivores =80%

Question 10

Production efficiency

Answer 10

-Proportion of assimilated biomass used to produce new consumer biomass

Question 11

Energy lost between trophic levels

Answer 11

• 2nd law of thermodynamic: energy is lost during transfer due to an increase in entropy(disorder)
• 90% lost at each transfer

Question 12

Trends in Biomass

Answer 12

-Most PP in aquatic systems takes place in phytoplankton
~compared to plants, a greater portion is digestible
-Primary producers are quickly consumed in aquatic systems
-although they differ in biomass, they do NOT differ in energy trends

Question 13

NPP is limited by climatic factors

Answer 13

• correlated with temp and precipitation

- range of conditions for photosynthesis

Question 14

NPP can be limited by nutrients

Answer 14

• Nitrogen, phosphorus, calcium, potassium

- more nutrients = more NPP

Question 15

Patterns of NPP in water

Answer 15

~NPP primarily limited by nutrient and light availability in aquatic systems
-phosphorous and nitrogen are the major limiting nutrients
~highest rates in oceans are in zones of upwelling

Question 16

Global NPP patterns

Answer 16

-highest rates on land are in tropics

~due to growing season, light, and precipitation

Question 17

Nutrients

Answer 17

elements that are required for the development,maintenance, and reproduction of organisms
~diff. from energy in that they aren’t lost in transfer (not a one-way trip)

Question 18

Nutrients in organisms

Answer 18

-five elements make up 93-97% of biomass of plants, animals, fungi, and bacteria: Carbon, Oxygen, Hydrogen, Nitrogen, Phosphorus.
~limiting nutrients are Nitrogen and phosphorus

Question 19

Agriculture and N-and P- cycling

Answer 19

Harber-Bosch process

agriculture has dramatically increased N and P inputs to terrestrial plants communities

Question 20

Eutrophication

Answer 20

the transformation of an ecosystem from low nutrient levels to high nutrient levels

• Usually caused by humans
• Produced bottom-up changes in communities

Question 21

Decomposition

Answer 21

The breakdown of organic matter accompanied by release of CO2