Ecosystems 2 - Energy Flow & Matter Cycles

Question 1

Energy in Trophic Levels

Answer 1

roughly 90% of energy is lost between each level transfer, which limits the length of food chains in a food web

Question 2

Energy is used in organisms for

Answer 2

• maintenance of the organism
• growth and reproduction
• lost as heat or excreted waste

Question 3

Implications of Energy Trophic Level Loss

Answer 3

• Pop. size of top predators remain small while the pop size and biomass of producers needs to be huge

Question 4

Biomass

Answer 4

combined mass of all organisms of that species/group in the ecosystem

Question 5

Biomagnification/Bioaccumulation

Answer 5

the concentration of toxins in an organism as a result of ingesting other plants/animals
- consumers accumulate higher toxin concentrations with each trophic position

Question 6

ELEMENTAL CYCLES

Answer 6

• matter is NOT lost that way that energy can leave the system as heat
• matter is retained in some form in the ecosystem

Question 7

Compartments

Answer 7

where matter is stored

Question 8

Flux

Answer 8

movement of matter between compartments

Question 9

CARBON CYCLE

Answer 9

• Carbon is stored in rock, plants, the ocean
• Carbon can flux due to photosynthesis, respiration, decomposition, and burning
• Carbon cycles quickly through individual organisms, but very slowly through the environment
• ROCK IS THE BIGGEST CARBON COMPARTMENT ON EARTH

Question 10

“Carbon Sink”

Answer 10

term for rock; because the carbon in rock is unavailable for use, buried deep in the Earth
- Tropical forests = missing “carbon sink”

Question 11

Carbon Cycle Trends

Answer 11

• increase in CO2 over time
• each year the global atmospheric carbon cycles with a steady pattern that represents the global terrestrial photosynthesis
• CO2 rises in the fall-winter, falls in the summer-spring

Question 12

Nitrogen Cycle (Book)

Answer 12

• cycles between reservoirs
• makes up 78% of the atmosphere as gas, but is not usable by most living things
• cycles via nitrogen fixation, ammonification, nitrification, assimilation, decomposition, denitrification

Question 13

Pyramids of Biomass and Energy

Answer 13

• energy flow always decreases with trophic level
• biomass usually decreases with trophic level
• oceans are different!

Question 14

Ecological Efficiency

Answer 14

E=NPn / NPn-1

E = Ecological efficiency
Npn = net production of TL n
NPn-1 = net production of TL(n-1)

Question 15

Nitrogen Cycle (Lecture)

Answer 15

• the cycle is strongly driven by biological processes
• N often limits primary production in terrestrial and aquatic systems
• human activities have fundamentally altered the terrestrial N cycle

Question 16

Eutrophication and Hypoxia

Answer 16

• N inputs to coastal waters often promote algal blooms
• coastal eutrophication promotes hypoxia and “dead zones”

Question 17

Eutrophication

Answer 17

the process in which a water body becomes overly enriched with nutrients, leading to the plentiful growth of simple plant life

Question 18

Hypoxia

Answer 18

a condition in which the environment has low or depleted oxygen levels, making it difficult for most aerobic life to survive

Question 19

Carbon Cycle: Hemispheres

Answer 19

in the northern hemisphere during the spring-summer, photosynthesis reduces atmospheric CO2

Question 20

Which of the following fluxes of C is currently the largest?

Answer 20

absorption of CO2 by the ocean

Question 21

Biotic VS Abiotic

Answer 21

Abiotic = non-living components of the ecosystem (EX: climate, sunlight, temperature, humidity)

Biotic = living components of the ecosystem (EX: organic matter, living things)

Question 22

NPP VS GPP

Answer 22

GPP: organic matter formed from inorganic matter by primary producers

NPP: the amount of energy resources left for the consumers in the ecosystem to acquire through herbivory after cellular respiration