Which element functions BOTH as an enzyme cofactor and as a stabilizer of ribosomes and nucleic ...

Which element functions BOTH as an enzyme cofactor and as a stabilizer of ribosomes and nucleic acids?
 
  A) iron
  B) hydrogen
  C) zinc
  D) magnesium

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All microorganisms require
 
  A) carbon, iron, and sodium.
  B) phosphorus, aluminum, and sodium.
  C) calcium, potassium, and magnesium.
  D) phosphorus, selenium, and sulfur.

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Which of the following statements is FALSE?
 
  A) Most bacteria are capable of using ammonia as their sole nitrogen source.
  B) Some bacteria are able to use nitrates or nitrogen gas as their nitrogen source.
  C) Most available nitrogen is in organic forms.
  D) Nitrogen is a major component of proteins and nucleic acids.

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Which of the following would be used by a chemoorganotroph for energy?
 
  A) C2H3O2-
  B) H2
  C) CO2
  D) H+

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Based on the functional roles of phosphate in various microbial metabolisms, deduce which compounds phosphate exists as in microorganisms.
 
  A) organic compounds
  B) inorganic compounds
  C) both organic and inorganic compounds
  D) neither organic nor inorganic compounds