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Difficulty: EasyNutrient and Biogeochemical Cycles

Match each nitrogen cycle microorganism on the left with its correct biological role on the right.

  • AzotobacterFree-living nitrogen fixation in soil
  • NitrosomonasOxidation of ammonia into nitrite
  • NitrobacterOxidation of nitrite into nitrate
  • PseudomonasConversion of nitrate into atmospheric nitrogen

Answer

Azotobacter matches Free-living nitrogen fixation in soil; Nitrosomonas matches Oxidation of ammonia into nitrite; Nitrobacter matches Oxidation of nitrite into nitrate; Pseudomonas matches Conversion of nitrate into atmospheric nitrogen.
Each microorganism has a distinct biochemical role in maintaining the balance of nitrogen compounds within ecosystems: Azotobacter fixes free atmospheric nitrogen into soil, Nitrosomonas oxidizes ammonia into nitrite, Nitrobacter oxidizes nitrite into nitrate, and Pseudomonas reduces nitrates back to nitrogen gas.

Step-by-Step Solution

1
Identify the metabolic role of Azotobacter
Free-living nitrogen fixation in soil
Azotobacter fixes nitrogen independently without forming symbiotic nodules on plant roots.
2
Identify the metabolic role of Nitrosomonas
Oxidation of ammonia into nitrite
Nitrosomonas converts ammonia compounds into nitrite as the first stage of nitrification.
3
Identify the metabolic role of Nitrobacter
Oxidation of nitrite into nitrate
Nitrobacter oxidizes the toxic intermediate nitrite into bioavailable nitrate.
4
Identify the metabolic role of Pseudomonas
Conversion of nitrate into atmospheric nitrogen
Pseudomonas participates in denitrification, returning nitrogen gas back to the atmosphere.

Key Concept

Microbial roles in the nitrogen cycle
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Topics

Nutrient and Biogeochemical Cycles

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