Chapter 20

Question 1

Define potential energy

Answer 1

Stored energy that is available/capable of performing work

Question 2

Define kinetic energy

Answer 2

Energy of motion. Energy that is currently performing work

Question 3

What is the first law of thermodynamics?

Answer 3

Conservation of energy - energy is neither created nor destroyed

Question 4

What is the 2nd law of thermodynamics?

Answer 4

Energy transfers - When energy is transferred, entropy increases

Question 5

Define entropy

Answer 5

The idea of chaos in a system. The state of disorder, randomness or uncertainty.
CANNOT do work.

Question 6

What is an example of entropy?

Answer 6

• 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.

Question 7

Define primary productivity

Answer 7

Rate at which autotrophs convert CO2 into organic compounds
(inorganic -> biomass)

Question 8

What is a chemoautotroph?

Answer 8

Autotroph that converts CO2 into organic compounds through chemical compounds

Question 9

What is a photoautotroph?

Answer 9

Autotroph that converts CO2 into organic compounds through sunlight.

Question 10

What is GPP

Answer 10

Gross Primary Productivity. Total rate of photosynthesis by autotrophs

Question 11

What is NPP

Answer 11

Net Primary Productivity. The rate of energy from organic molecules being stored after energy is expended from cellular respiration

Question 12

How is Rate of Production expressed?

Answer 12

kcal/m^2/yr
Units of energy / Unit area / Unit of time

Question 13

What regulates secondary productivity?

Answer 13

Primary productivity

Question 14

What 3 things affect terrestrial primary productivity?

Answer 14

Precipitation
Temperature
Nitrogen Availability

Question 15

What is the relationship between NPP and length of growing season?

Answer 15

The longer the growing season, the increase of net productivity.

Question 16

What is the relationship between PAR and water depth?

Answer 16

PAR declines exponentially with increase in water depth.

Question 17

What is PAR?

Answer 17

Photosynthetically active radiation. Essentially wavelengths that autotrophs can photosynthesize.

Question 18

Where is photosynthetic rate and GPP highest in relation to PAR?

Answer 18

Highest at intermediate levels of PAR.

Question 19

What is compensation depth?

Answer 19

When GPP = R (respiration rate). This means that NPP = 0.

Question 20

In aquatic systems specifically, what are limiting factors for NPP and why?

Answer 20

Nutrients (nitrogen, phosphorus, iron)
due to nutrients from deeper ocean waters needing to be transported to surface waters for photosynthesis.

Question 21

What 3 things did nutrient enrichment experiments teach us:

Answer 21

• Nitrogen addition stimulates phytoplankton the most
• Iron follows closely in stimulating growth
• Phosphorus addition did not really stimulate growth.

Question 22

What does Iron do?

Answer 22

Is a cofactor of most enzymes. Allows for correct folding of proteins — specifically nitrogenase.

Question 23

What are limiting factors for NPP in stream ecosystems?

Answer 23

light and nutrient availability.
Canopy cover above the stream affects light availability.

Question 24

What is an autochthonous carbon

Answer 24

Carbon produced within an aquatic ecosystem.
Comes from photosynthesis by plants, algae, and phytoplankton

Question 25

What is an allochthonous carbon

Answer 25

Carbon produces outside an aquatic ecosystem. Comes from dead organic matter from adjacent terrestrial ecosystems Can be DOM or POM

Question 26

What is DOM? POM?

Answer 26

Dissolved organic matter (DOM) Particulate organic matter (POM)

Question 27

What is the river continuum concept?

Answer 27

Continuum along a flowing body of water of the importance of allochthonous and autochthonous carbon sources.

Question 28

Small streams will have a majority of ____________ carbon due to _____________.

Answer 28

Allochthonous carbon due to canopy cover.

Question 29

As streams increase in size, relative abundance of allochthonous carbon _____ while autochthonous carbon _____ due to a ______ in canopy cover.

Answer 29

decreases, increases, decrease

Question 30

How does NPP change in later stages of succession?

Answer 30

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.

Question 31

A system with high allochthonous carbon has an increased number of ________?

Answer 31

decomposers

Question 32

A system with high autochthonous carbon has an increased number of ________?

Answer 32

filter feeders

Question 33

What is secondary production?

Answer 33

AKA secondary productivity. Net energy allocated to production...... formation of living heterotroph biomass over a period of time

Question 34

Heterotroph biomass is equal to...

Answer 34

autotroph NPP (grams/area/time)

Question 35

When is secondary production the greatest?

Answer 35

When the birthrate of the population and the growth rate of individuals is the highest.

Question 36

What is "The World is Green" proposition?

Answer 36

Plant biomass accumulates because predators keep the herbivore population in check. (top-down control!)

Question 37

What is trophic cascade? What is it caused by?

Answer 37

Changes in the population at the top of the food chain trigger a chain reaction that affects species at lower levels. Top-down control.

Question 38

Food ingested by a consumer can be either (2 things):

Answer 38

Assimilated in the gut (A) OR Expelled from the body as waste (W)

Question 39

Food assimilated in the gut can then be used during (2 things):

Answer 39

Respiration (R) - body maintenance Production (P) - growth, development, reproduction

Question 40

What is Assimilation Efficiency?

Answer 40

A / I ---- measures the efficiency of extracting energy from food I = consumer

Question 41

What is Production Efficiency?

Answer 41

P / I ----- measures how efficiently assimilated energy is incorporated into secondary production.

Question 42

What is detritus?

Answer 42

Organic material derived from dead/decaying organisms (Fallen leaves, animal carcass, etc.)