Topic 12 - Ecosystem Energetics

Question 1

Ecosystems

Answer 1

communities of
organisms interacting with their physical
environment under the influence of
environmental factors

Question 2

ecosystem energetics

Answer 2

the study of
how energy is fixed by autotrophs and
made available to heterotrophs

Question 3

how is energy measured in ecosystem energetics

Answer 3

it is measured as biomass

Question 4

What is the first trophic level

Answer 4

primary producers

Question 5

What are primary producers

Answer 5

Autotrophic organisms that fix inorganic
nutrients (C, N, P, O, etc.) into organic
molecules

Question 6

Primary productivity

Answer 6

The rate at which energy is fixed

Question 7

Gross primary production

Answer 7

total amount energy fixed into organic molecules in an ecosystem

Question 8

Net primary production

Answer 8

what producer makes - what the producer uses for itself
measured as biomass

Question 9

What factors affect primary productivity

Answer 9

Light
Temperature
Precipitation
Nitrogen
Phosphorus
Carbon dioxide

Question 10

How does light affect primary productivity

Answer 10

as light intensity increases, Primary productivity increases

However too much light causes damage

Question 11

how does temperature affect primary productivity

Answer 11

as temperature increases, net primary productivity increases

Question 12

how does precipitation affect primary productivity

Answer 12

As precipitation increases, net primary productivity increases

However, too much precipitation and there isnt enough sun

Question 13

how does nitrogen affect primary productivity

Answer 13

N is soluble, it washes away with rainfall, tends to be more limiting on land

a temperate grassland has high NPP increase with N addition

Question 14

how does phosphorus affect primary productivity

Answer 14

P is used in DNA synthesis, insoluble in water, more limiting in aquatic ecosystems

As P increases, mean anual chlorophyll increases

Question 15

how does carbon dioxide affect primary productivity

Answer 15

higher CO2 can increase plant growth, as long as all other nutrients are in place

Question 16

What is the second trophic level

Answer 16

Primary consumers (Herbivores)

Question 17

What are PCs

Answer 17

organisms that consume the biomass of primary producers
they use the energy consumed to support their energy budget
excess turns into new biomass

Question 18

What is biomass production

Answer 18

secondary (there is no tertiary) production

Question 19

What is the third/fourth trophic level

Answer 19

secondary/tertiary consumers (carnivores/omnivores)

Question 20

What are Consumers

Answer 20

consume biomass of consumers in a lower trophic level

Question 21

What are decomposers/detritivores

Answer 21

Organisms that consume the dead
organic matter of primary
producers, primary consumers

Question 22

what type of production do decomposers do?

Answer 22

secondary production

Question 23

In a food web, what happens to the energy

Answer 23

flows through the ecosystem, energy is lost as heat

Question 24

What forces regulate trophic structure

Answer 24

bottom up control
top down control

Question 25

What is bottom-up control of trophic structure

Answer 25

resource abundance regulates
energy in each trophic level is determined by energy in the lower trophic level

Question 26

Oligotrophic

Answer 26

normal limits

Question 27

Eutrophic

Answer 27

phytoplankton bloom, excess nutrients

Question 28

Eutrophic cascade

Answer 28

algae bloom, zooplankton eats and population grows which consumes oxygen, then fish die

Question 29

what is top-down control of trophic structure

Answer 29

predation regulates, organisms in each trophic level are limited by predators in the next higher trophic level

Question 30

Trophic cascade

Answer 30

removing a top predator results in a cascade effect - alternating increase/decrease at each trophic level

Question 31

Keystone species

Answer 31

important to the trophic structure

can be small in number but have big impact when removed, not a trophic cascade

Question 32

nutrients

Answer 32

elements required by organisms

Question 33

biogeochemical cycles

Answer 33

Pathways that describe how nutrients move
between biotic and abiotic components of an
ecosystem

Question 34

Explain how nutrients are in reservoirs

Answer 34

reservoirs can be short or long term (200 years)
can be biotic or abiotic (biotic=organic)

Question 35

What are the three major geological nutrient reservoirs

Answer 35

terrestrial, aquatic, atmostpharic

Question 36

What is the generalized compartment model

Answer 36

Short term Longterm
available organic and inorganic,
unavailable organic and inorganic

Question 37

What is the carbon cycle

Answer 37

carbon is the most abundant element in organisms - 50% of dry mass

carbon is the unit of energy currency in organisms and ecosystems

carbon cycles through all four nutrient compartments

Question 38

What is the long term carbon cycle

Answer 38

recent increase in CO2, concerning because it isnt going down like in previous cycles and rising much faster than previous

Question 39

What is the greenhouse effect

Answer 39

the earth eventually radiates the energy absorbed from the sun back into space

Question 40

what are the three important GHGs

Answer 40

CO2 CH4 N2O

Question 41

what happens to excess carbon

Answer 41

anthropogenic CO2 generation has increased, half stays in the atmosphere

Question 42

what happens to anthropogenic CO2 that is absorbed by the oceans

Answer 42

CO2 and water react to form carbonic acid resulting in ocean acidification

carbonic acid dissociates releasing bicarbonate

shells recruire carbonate, thus they are left culnerable

Question 43

What happens to anthropogenic CO2 that is absorbed by the oceans