Topic 12: Ecosystem Energetics

Question 1

Ecosystem

Answer 1

community of organisms interacting with their environment under influences of environmental factors

Question 2

Ecosystem energetics

Answer 2

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

Question 3

autotrophs

Answer 3

producer - organisms that form nutrional organic substances (ie CO2)

Question 4

heterotrophs

Answer 4

consumers - organisms able to derive nutritional requirements from complex organic substances

Question 5

energy is measured as

Answer 5

Biomass

Question 6

biomass

Answer 6

dry weight of organic matter

Question 7

Primary producers

Answer 7

• 1st trophic level
• autotrophs that fix inorganic nutrients into organic molecules
• carry out primary production

Question 8

Primary productivity

Answer 8

rate at which energy is fixed

Question 9

Net primary production

Answer 9

what producer makes - what producer uses

• tells us how much energy is left for other trophic levels

Question 10

Gross primary production

Answer 10

total amount of energy fixed into organic molecules in an ecosystem

Question 11

5 things that affect primary production

Answer 11

light, temperature, precipitation, nitrogen and phosphorous concentrations

Question 12

Light

Answer 12

know graph and 2 important points on it

• start of plateau = more light than enzyme can handle
• end of plateau & decrease because UV damange and radiation due to too much light decreases PP

Question 13

Precipitation

Question 14

temperature

Answer 14

pp increases as temperature increases bc enzyme reactions increase with temperatrue

Question 15

nitrogen

Answer 15

deficiency is more in terrestrial as N is soluble in water

• limiting factor in terrestrial

Question 16

phosphorous

Answer 16

limiting factor in aquatic as it is insoluble

Question 17

increasing a limiting factor will cause a ___________ impact

Answer 17

greater

Question 18

Primary consumers

Answer 18

2nd trophic level
- energy consumed (Ein) to support its energy budget
- herbivores
- biomass production is called secondary production

Question 19

Secondary/Tertiary Consumers

Answer 19

3rd/4th trophic levels
- omnivores/carnivores
- energy consumed (E in) is used to support energy budget
- biomass production is called secondary production

Question 20

Decomposers/detritivores

Answer 20

• cycle nutrients
• do secondary production

Question 21

nutrients are always ______

Answer 21

cycled

Question 22

energy always ________ in ___________, and is lost as _______

Answer 22

flows; one direction; heat

Question 23

Ecological Efficiency

Answer 23

transfer of energy from one trophic level to another
- usually around 10%

Question 24

EE=

Answer 24

(net primary productivity of higher TL)/(net primary productivity of lower TL) x 100%

Question 25

Assimilation

Answer 25

amount of energy taken up

Question 26

Keystone Species

Answer 26

critically important in maintenance of trophic structure; usually small in number

Question 27

Forces that regulate trophic structure: (3)

Answer 27

bottom-up control, top-down control, trophic cascade

Question 28

Bottom-up control

Answer 28

resource abundance regulates trophic structure - how energy in lower levels determines energy in higher levels

Question 29

Top-down control

Answer 29

predation regulates trophic structure

Question 30

Trophic cascade

Answer 30

changing a top predator often results in a cascading/alternating effect down the food chain

Question 31

nutrients

Answer 31

elements required by organisms; cycled; in reservoirs

Question 32

biochemical cycles

Answer 32

pathways describing how nutrients move between biotic and abiotic components

Question 33

short term reservoirs hold nutrients for ___ 200 yrs

Answer 33

less than

Question 34

long term reservoirs hold nutrients for ___ 200 yrs

Answer 34

more than

Question 35

3 major nutrient reservoirs

Answer 35

terrestrial, aquatic, atmospheric

Question 36

3 states of nutrients:

Answer 36

gas, soluble, insoluble

Question 37

Generalized compartment model

Answer 37

available organic
available inorganic
unavailable organic
unavailable inorganic

Question 38

Carbon cycle

Answer 38

carbon makes up 5% of dry mass; most abundant nutrient; unit of energy currency; glucose (carbon chain) essential for energy transfer; cycles through all 4 nutrient compartments

Question 39

Short-term carbon cycle

Answer 39

carbon increases (CO2) in winter because humans burn for heat; carbon decreases in summer as more plants use it

Question 40

Long-term carbon cycle

Answer 40

carbon content (CO2) has increased due to human activity

Question 41

Carbon isotopes

Answer 41

C^12 = 99% - most organisms and P/S prefer this; fossil fuels are mostly made up of C^12

Question 42

Green House Effect

Answer 42

result of change of gases in atmospheric section; earth radiates energy absorbed from sun back to space

Question 43

Greenhouse gases increase

Answer 43

prevents earth from radiating energy back into space

Question 44

Anthropogenic CO2 absorbed by the ocean reacts with ___ to form __________, which turns into ____________ and ______ the pH

Answer 44

H2O; carbonic acid; bicarbonate; lowers