Download 1. Distinguish between trophic structure and trophic

Chapter 54 Reading Quiz
1.
Which trophic level ultimately supports
all of the others?
2. What 2 things limit primary productivity
in aquatic ecosystems?
3. Which biogeochemical cycle includes
evaporation & precipitation?
4. Which biogeochemical cycle includes
photosynthesis & cellular respiration?
1. Distinguish between trophic
structure and trophic levels.
• Trophic structure  the feeding
relationships in an ecosystem that
determine the paths of energy flow and
chemical cycling
• Trophic levels  ecologists divide the
species in a community or ecosystem into
different trophic levels based on their
main source of nutrition 
2. Overview primary consumers and producers. How
are these different from secondary consumers?
Tertiary consumers? List examples.
• Primary producers  autotrophs that
support all other trophic levels either
directly or indirectly by making sugars
• Primary consumers  herbivores that
consume primary producers
• Secondary consumers  carnivores that
eat the herbivores
• Tertiary consumers  carnivores that eat
the other carnivores 
3. What are detritivores? What do they eat?
• Detritivores  (decomposers) consumers
that derive energy from detritus (organic
waste) and dead organisms from other
trophic levels
• These form a major link between primary
producers and the consumers in the
ecosystem 
4. Differentiate between a food chain and a food
web. How does production differ from
consumption differ from decomposition?
• Food chain  the pathway along which food is
transferred from trophic level to trophic level,
beginning with primary producers
• Food web  the elaborate feeding relationships
between the species in an ecosystem
• Production  the rate of incorporation of energy
and materials into the bodies of organisms
• Consumption  refers to the metabolic use of
assimilated organic molecules for organismal
growth and reproduction
• Decomposition  the breakdown of organic
molecules into inorganic molecules 
5. Overview how energy flows through an
ecosystem.
• Energy for growth, maintenance, and
reproduction is required by all organisms
• The ecosystem’s budget relies on primary
productivity
• Light  Plants  Animals 
Bacteria/Fungi 
6. Distinguish between gross primary
productivity and net primary productivity.
• Gross primary productivity  the total
amount of light energy converted to
chemical energy by autotrophs of an
ecosystem (measured by the oxygen
produced)
• Net primary productivity  is the GPP
minus the energy used by producers for
respiration
- the organic mass available to consumers

7. What is biomass? What is a limiting
nutrient?
• Biomass  how primary productivity is
expressed as amount added to an
ecosystem per unit area per unit time
(g/m2/yr) or energy (J/m2/yr)
• Limiting nutrient  when a nutrient has
been removed in such quantities that
sufficient amounts are no longer available

8. Overview the ecological pyramids.
• The transfer of energy from one trophic
level to the next is not 100%
• Energy flows through an ecosystem, it does
not cycle
• The pyramids can symbolize:
1. Productivity in the trophic levels
2. Biomass
3. Numbers of individuals 
9. List the biogeochemical cycles. Why is it
necessary for nutrients to cycle?
•
Biogeochemical cycles  nutrient circuits
involving both biotic and abiotic
components of ecosystems
1. Water
2. Carbon
3. Nitrogen
4. Phosphorus
• Necessary for life to continue 
10. Overview the water cycle, the carbon
cycle, the nitrogen cycle, and the phosphorus
cycle.
• Water  evaporation, precipitation
• Carbon  photosynthesis, cellular respiration
• Nitrogen  needed for amino acids, nitrogen is
fixed, plants take it up, animals eat the plants,
death and waste enter soil, bacteria nitrify it back
to the atmosphere
• Phosphorus  needed for nucleic acids,
membranes, ATP, short and long term cycles 
11. Describe what happens in decomposition.
• The rate of decomposition has a great
impact on the timetable for nutrient
cycling
• In tropical rain forests: months to years
• In temperate forests: 4 – 6 years
• In the tundra: over 50 years
• Soil chemistry and fire frequency influence

12. How does vegetation regulate chemical
cycling?
• Plants retain nutrients within an ecosystem
• If logging and deforestation occur, less
nutrients are retained in that area 
13. How are human populations disrupting
chemical cycles?
• Often humans remove nutrients from one
part of the biosphere and add them to
another
• Farming exhausts nutrients in an area, and
then causes runoff of fertilizers and waste
• From this, disruptions can flow from one
ecosystem to another 
14. Describe the concept of “biological
magnification”.
• Biological magnification  the process by
which toxins become more concentrated
with each successive trophic level of a food
web; results from biomass at each trophic
level being produced from a much larger
biomass ingested from the level below
• Ex: mercury and tuna fishing 
15. Describe how humans are causing changes
in the atmosphere.
• Carbon dioxide emissions and the
greenhouse effect
- CO2 doesn’t escape the earth
• Depletion of atmospheric ozone
- O3 is broken apart and does not provide
the protection from UV rays 