Download Due: October 6, 2006

APES
Fall 2006
Chapter 3 Question Set Answers
Due: October 6, 2006
1. Identify the five major “levels of organization of matter” which the field of ecology focuses on: Organism,
population, community, ecosystem and biosphere
2. Distinguish between the following: population, community, and ecosystem. Population consists of a group
of interacting organisms of the same species that occupy a specific area at the same time. Communities are
populations of different species occupying a particular place. Ecosystems are communities of different species
interacting with one another and their nonliving environment.
Biospher
3. Describe each of the following:
a) lithosphere – the earth’s crust and upper mantle e
b) hydrosphere – the earth’s liquid water, ice, and water vapor
c) atmosphere – the air around the planet
d) ecosphere/biosphere – all the living organisms and the parts they interact with
4. Describe what abiotic ecosystem components are; include 3 examples. Abiotic components are all the
nonliving physical and chemical factors that influence living organisms in an ecosystem. Examples are sunlight,
temperature, precipitation, wind, latitude, altitude, soil, water current, light penetration, nutrients, salinity, etc.
5. How does the optimum range relate to the range of tolerance? (For a given species and a specific abiotic
factor, such as a Golden Trout and water temperature.) The optimum range is the narrow band in which a
species may do best at within the range of tolerance.
6. What does the Limiting Factor Principle state? The limiting factor principle states that too much or too little
of any abiotic factor can limit or prevent growth of a population even if all other factors are at or near the
optimum range of tolerance.
7. Write the chemical equation for photosynthesis.
6CO2 + 6H2O + solar energy = C6H12O6 + 6O2
8. Write the chemical equation for cellular respiration.
C6H12O6 + 6O2 = 6CO2 + 6H2O + energy
9. What other category of producers exist besides the photosynthetic producers? Identify 2
locations/environments where you might find such non-photosynthetic producers. Chemosynthetic
producers – they are found in hydrothermal vents in the ocean’s depths, and in areas deep within the earth’s
crust
10. Identify and distinguish between six types of consumers.
1) Herbivores – plant eaters
2) Carnivores – meat eaters
3) Omnivores – plant and meat eaters
4) Scavengers – feed on dead organisms
5) Detritus feeders - feed on decomposing organic matter
6) Decomposers – break down organic matter and release it back to the nutrient cycle
11. Approximately what percent of the kilocalories found in the “preceding” or lower trophic level actually
become incorporated into the tissues of organisms in the trophic level directly above it? 10%
12. From the above question, what happens to the remainder of the kilocalories (those that do not make it in
to the biomass of the consumer organisms feeding on the trophic level below them? It is converted into
heat.
13. If there are 1,000,000 kilocalories in the producer level of an energy pyramid, how many kilocalories will
be incorporated into the bodies of the:
a) primary consumers? 100,000 kcal
b) secondary consumers? 10,000 kcal
c) tertiary consumers? 1,000 kcal
14. Briefly describe the seven main processes involved in the hydrologic cycle:
1) evaporation – conversion of water into water vapor
APES
Fall 2006
2) transpiration – evaporation from leaves of water extracted from soil by roots and transported throughout the
plant
3) condensation – conversion of water vapor into droplets of liquid water
4) precipitation – rain, sleet, hail or snow
5) infiltration – movement of water into soil
6) percolation – downward flow of water through soil and permeable rock to groundwater storage areas
7) runoff – downslope surface movement back to the sea
15. Name the two driving forces behind the water cycle: Sun and gravity.
16. Why is it necessary that biogeochemical cycles exist? Explain: Biogeochemical cycles bring the necessary
nutrient that organisms need to live, grow and reproduce.
17. Relate the following terms: groundwater, aquifer, and water table. Groundwater is the name of water found
underground. It is stored in permeable rocks called aquifers. The top of the groundwater is called the water
table.
18. Describe three significant anthropogenic interventions in the hydrological cycle.
1) Withdrawing large quantities of fresh water
2) clearing vegetation
3) modifying water quality.
19. Provide three specific ways in which carbon is essential for biota to function:
1) It is a building block for carbs, fats, proteins, DNA
2) It is a key component in the earth’s thermostat (as CO2)
3) It is used in photosynthesis
20. Identify the two processes, which have the greatest influence on tropospheric concentrations of carbon
dioxide on a monthly or yearly basis. Explain:
1) Diffusion of CO2 in the atmosphere into the ocean because it is readily soluble in water and is removed by
photosynthesizing producers
2) Burning of fossil fuels because we are taking a resource/reservoir that took millions of years to form and
adding it to the atmosphere in a couple of hundred years.
21. Name the two largest sinks (storage areas) for carbon; briefly explain how these areas have become such
substantial carbon sinks. Ocean sediments and continental rocks because the carbon from these areas are
cycled very slowly so they are allowed to build up over time.
22. Describe the two major human interventions in the carbon cycle.
1) Burning of fossil fuels
2) Deforestation and vegetation removal.
23. Why is the nitrogen cycle significant to biota? Organisms need nitrogen to make many organic compounds
(proteins, DNA, and RNA)
24. Identify the two major ways that nitrogen is fixed;
1) By cyanobacteria in soil and water
2) Rhizobium bacteria living in small nodules on the root systems of certain plants
25. Describe what takes place in each of the following processes or steps of the N-cycle
a. Nitrogen fixation – specialized bacteria convert gaseous nitrogen to ammonia (NH3) that can be used by
plants.
b. Nitrification – the ammonia in soil is converted by specialized aerobic bacteria to nitrite ions (NO2-),
which are toxic to plants and nitrate ions (NO3-), which are easily taken up by the plants
c. Assimilation – plant roots absorb inorganic ammonia, ammonium ions, and nitrate ions and use these
ions to make nitrogen-containing organic compounds (DNA, proteins)
d. Ammonification – specialized decomposer bacteria convert the nitrogen-rich organic wastes into
ammonia (NH3) and ammonium ions (NH4+)
e. Denitrification – specialized bacteria convert the ammonia and ammonium ions back into nitrite and
nitrate ions and then into nitrogen gas and nitrous oxide (N2O)
26. Identify the major sinks for nitrogen. 1) the atmosphere (78% N2), and 2) in continental rocks
27. Describe seven anthropogenic interventions in the nitrogen cycle.
APES
Fall 2006
1) Adding large amounts of nitric oxide (NO) into the atmosphere when we burn fuel
2) Adding nitrous oxide (N2O) to the atmosphere through the action of anaerobic bacteria on livestock wastes
and fertilizers
3) Removing nitrogen from topsoil
4) Adding nitrogen compounds to aquatic systems
5) Accelerating the deposition of acidic nitrogen compounds from the atmosphere onto terrestrial ecosystems
28. How is phosphorous important to biota? It is an essential nutrient of both plants and animals (DNA, ATP,
certain fats, and bones, teeth and shells)
29. Explain why phosphorous does not circulate in the troposphere to a great extent: There are no common
gaseous forms of phosphorous, and is only found in the atmosphere as particles of dust.
30. Identify the largest sinks for phosphorous: 1) Terrestrial rocks, 2) ocean sediments, and 3) water
31. Comment on how human activities have influenced the phosphorous cycle regarding each of the
following:
a. Mining phosphate rock – adds phosphates to water systems in the form of runoff
b. Deforestation – reduces the amount of phosphates in the soil
c. Animal wastes from livestock feedlots – increase the amount of phosphate in the soil and the local fresh
water
d. Commercial phosphate fertilizers in agricultural areas - increase the amount of phosphate in the soil and
the local fresh water
e. Discharge of municipal sewage/wastewater treatment facilities - increase the amount of phosphate in the
soil and the local fresh water
32. How is sulfur significant to biota? In the atmosphere, sulfur can be converted into sulfuric acid which is
harmful to plants and animals.
33. Identify the two largest storage areas for sulfur: 1) Terrestrial rocks and 2) ocean sediments
34. Identify the major natural sources of each of the following sulfur compounds:
a) H2S – active volcanoes
b) SO2
- volcanoes
c) SO42- - sea spray
d)CH3SCH3 (dimethyl sulfide, or DMS) – certain marine algae
35. Explain the chemical transformations (reactions) which occur when SO2 reacts with O2 and H2O in the
troposphere to eventually become sulfuric acid: Sulfur dioxide reacts with oxygen to form sulfur trioxide gas
(SO3). Some of this sulfur trioxide gas reacts with water vapor to produce tiny droplet of sulfuric acid (H2SO4).
36. Identify the three major human activities influencing the sulfur cycle:
1) Burning sulfur-containing coal and oil to produce electric power
2) Refining sulfur-containing petroleum to make gasoline and heating oil
3) using smelting to convert sulfur compounds of metallic minerals into free metals such as copper, lead, and
zinc.