8 Exercises
Exercise 1
What is the most important difference between prokaryotic and eukaryotic microorganisms?
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Exercise 2
Describe the differences between prokaryotic cell walls that are distinguished by their response to the Gram stain.
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Exercise 3
What is produced by prokaryotic cells that allows them to not only adhere to mineral surfaces, protect against dehydration, and form biofilms but also contribute to the adsorption of dissolved ionic chemical substances from solution?
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Exercise 4
What is the doubling time for a microorganism with an exponential growth rate constant of 0.005 s-1?
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Exercise 5
Why is the magnitude of length scale such an important physical property for describing microbial habitats in groundwater systems?
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Exercise 6
Explain why shallow groundwater systems occurring in similar climates have the same average temperature.
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Exercise 7
Assuming a geothermal thermal gradient of 25 to 30°C per km, how would the temperature preference of microorganisms living at a depth of 2000 m be described?
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Exercise 8
You take a core sample from 20 m depth and break off a 3.5 g subsample of soil to analyze for microbial community composition. Based on the average cell density in subsurface materials at this depth, what is the approximate population of microorganisms contained in your subsample?
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Exercise 9
Place the following terminal electron acceptors for microbial respiration in order of decreasing potential metabolic energy yield. What are the corresponding conjugate reductants of the electron acceptors?
- Carbon dioxide
- Sulfate
- Fe(III)/Mn(IV)
- Oxygen
- Nitrate
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Exercise 10
What is the metabolic classification of subsurface prokaryotic microorganisms that use chemical compounds as a source of energy with inorganic substances serving as electron donors and carbon dioxide being fixed to make cellular biomass?
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Exercise 11
What is the metabolic classification of subsurface prokaryotic microorganisms that use chemical compounds as a source of energy with organic substances serving as both electron donors and a carbon source to make cellular biomass?
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Exercise 12
Why are shales and clay not especially good habitats for prokaryotic microorganisms?
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Exercise 13
As part of your hunt for evidence of micro-eukaryotes and prokaryotes at a field site, you take a core sample of carbonate rock. Would you expect to find both types of your target microorganisms, just one type, or neither? Explain.
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Exercise 14
Describe the ways in which prokaryotic microorganisms contribute to chemical reactions in groundwater systems.
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Exercise 15
Briefly explain the difference in pH sorption behavior between positively and negatively charged ions on sorbent solids in groundwater systems, including prokaryotic microbial cells surrounded by extracellular polymeric substances.
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Exercise 16
What role do microbes play in the cleanup of groundwater pollutants?
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Exercise 17
You are working as a hydrogeologist on a site where groundwater is contaminated with BTEX. You have been asked to provide a rationale for the use of bioremediation to remove the BTEX from the groundwater and provide and describe three possible bioremediation strategies to eliminate the target contaminants. Explain what groundwater conditions would enhance microbial remediation of the target contaminants and why? Assume that microorganisms that can degrade hydrocarbons are ubiquitous at your site.
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Exercise 18
In what way do groundwater microorganisms contribute to mineral dissolution reactions?
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Exercise 19
Explain why dissimilatory Fe(III)- and Mn(IV)-reducing bacteria are important for the reductive dissolution of oxide minerals in groundwater.
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Exercise 20
What are some applications of microbial carbonate mineral precipitation?
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