Biomes
Name three facts about the tundra.
- Coldest of all the biomes with little precipitation
- Contaminated soil is long-lasting due to the cold and very slow bacterial activity
- Permafrost - perennially subsoil found in the Arctic or Subarctic regions
- Treeless landscapes with simple vegetation structure
- Short growing and reproductive seasons
- Mammals and birds have extra layers of fat for insulation
- Environmental threats: construction of pipelines, influx of air pollution, invasive species, oil spills, ozone depletion, and gas, oil, and mineral exploration
Does oceanic absorption of CO2 make water more increase and decrease H+ concentration? Increase or decrease pH?
Increase [H+] and decrease pH.
CO2 absorption makes water more acidic, which affects ocean biosystems. The projected rate of increasing oceanic acidity could slow the biological precipitation of calcium carbonates, thus decreasing the ocean's capacity to absorb CO2.
The rate at which producers capture and store a given amount of chemical energy as biomass in a given length of time.
Gross Primary Productivity (GPP)
What do the first and second laws of thermodynamics state?
1. Energy cannot be created or destroyed.
2. When energy is converted from one form to another, a less useful form results (energy quality). Energy cannot be recycled to a higher quality.
Which food chain found on the Serengeti Plain is in the correct sequence from lowest trophic level to highest?
a) shrubs-gazelles-cheetahs-decomposers
b) shrubs-decomposers-cheetahs-gazelles
c) gazelles-decomposers-cheetahs-shrubs
d) decomposers-cheetahs-shrubs-gazelles
a) shrubs-gazelles-cheetahs-decomposers
What biome are these characteristics describing?
- Defined by the amount of rainfall (<10 inches per year), not by temperature
- Most are located north and south of the equator
- Evaporation rates regularly exceed rainfall rates
- Temperatures exhibit daily extremes because the atmosphere contains little humidity to block the Sun's rays
- Soils often have abundant inorganic nutrients and have little or no organic matter
Desert
Identify three major carbon reservoirs.
Sedimentary rock (limestone), oceans, fossil fuel deposits, soil organic matter, atmospheric CO2, and old-growth trees
What is the formula for NPP?
NPP = GPP - plant respiration
If 10,000 kcal of energy is available at the level of the producers, what is the amount of energy available at the level of tertiary consumers?
10 kcal
Which is produced during photosynthesis?
I. glucose
II. sulfur
III. carbon dioxide
a) I only
b) III only
c) I and III
d) II and III
Describe three facts about freshwater biomes.
Includes lakes, rivers, streams, creeks, and puddles.
Freshwater consists of ~2.5-3% of all water on Earth, with about 75% of that being used for irrigation.
Generally high in nutrition and minerals, allowing for a wide diversity of plants and animals.
Global warming and pollution have a huge impact on freshwater biomes because of their limited size.
Examples of human activity that have dramatically affected the natural nitrogen cycle since the industrial and 20th-century agricultural revolutions.
- Biomass burning which releases nitrogen-containing gases
- Extensive use of inorganic fertilizers
- Extensive cultivation of legumes primarily used in cattle feedlots
After a severe drought, the productivity in an ecosystem took many years to return to pre-drought conditions. This observation indicates that the ecosystem has
a) high resilience
b) low resilience
c) high resistance
d) low resistance
b) low resilience
Describe the 10% Rule. What is the exception to the 10% Rule?
When energy moves between trophic levels, only 10% of the energy is made available for the next higher level. The exception is the transition from the Sun to producers, in which case only 1% of the energy is retained.
At which trophic level do organisms use a process that produces oxygen as a waste product?
Producers
Describe three ecological services of wetlands.
Absorb excess water from flooding or storm surges.
Act as carbon sinks.
Provide recreational areas.
Provide areas for agriculture and timber.
Provide breeding grounds for many animals.
Briefly describe the five steps of the nitrogen cycle.
1. Nitrogen fixation: N2 to NH3/NH4+ or NO3-
2. Nitrification: NH3 to NO3-
3. Assimilation: incorporation of NH3 and NO3- into biological tissues
4. Ammonification: organic nitrogen compounds to NH3
5. Denitrification: NO3- to N2
Which aquatic biome has the lowest net primary productivity, measured as kilocalories of energy produced per square meter per year?
Open ocean
The NPP of an ecosystem is 1 kg C/m2/year, and the energy needed by the producers for their own respiration is 1.5 kg C/m2/year. The GPP of such an ecosystem would be
a) 0.5 kg C/m2/year
b) 1.5 kg C/m2/year
c) 2.0 kg C/m2/year
d) 2.5 kg C/mr/year
d) 2.5 kg C/mr/year
Small inputs of this substance, commonly a limiting factor in aquatic ecosystems, can result in algal blooms and dead zones.
a) dissolved CO2
b) sulfur
c) dissolved O2
d) phosphorus
d) phosphorus
Lakes are often classified according to their production of organic matter. What are the three general categories? Briefly describe each.
1. Oligotrophic (young lake) - deep, cold, small surface area relative to depth, nutrient-poor, phytoplankton are sparse, not very productive, don't contain much life, waters often very clear, and sediments are low in decomposable organic matter.
2. Mesotrophic (middle-aged lake) - moderate nutrient content and moderate amount of phytoplankton, reasonably productive.
3. Eutrophic (old lake) - shallow, warm, large surface area relative to depth, nutrient-rich, phytoplankton more plentiful and productive, waters often murky, high organic matter content in benthos, which leads to high decomposition rates and potentially low oxygen.
Describe three facts about the phosphorus cycle.
- Phosphorus does not enter the atmosphere but remains primarily in rock and soil minerals; it is part of a slow biogeochemical cycle.
- Phosphorus is found in DNA and RNA molecules, molecules that store energy (ATP and ADP), and cell membranes and bones.
- Weathering of rocks releases phosphorus in a soluble form, which allows plants to absorb phosphates from the soil and then incorporate them into organic compounds.
- Phosphates cause algae to grow rapidly; their decomposition eventually depletes the oxygen supply in the water.
- Excessive logging removes phosphates stored under trees, and rain washes remaining sink into aquatic systems.
Open oceans produce the largest share of Earth’s biomass because the net primary productivity (NPP) of the oceans is
a) high and thus can support a high proportion of producers
b) high as a result of the high concentration of nutrients in the open oceans
c) low, but the large expanse of the oceans supports enormous numbers of producers such as phytoplankton
d) low, but the individual producers found there are huge in size
c) low, but the large expanse of the oceans supports enormous numbers of producers such as phytoplankton
Which of the following best explains why decomposers in soils and water are important to ecosystems?
a) They remove heavy metals
b) They store CO2
c) They recycle nutrients
d) They neutralize acid deposition
c) They recycle nutrients
Which of the following is a process that indirectly removes carbon from Earth's atmosphere?
a) Formation of carbonate deposits
b) Outgassing by volcanoes
c) Respiration by mammals
d) Respiration by anaerobic bacteria
a) Formation of carbonate deposits