The enzyme complex that catalyzes the conversion of atmospheric nitrogen to ammonia is __________.

• A. rhizobium
• B. leghemoglobin
• C. rubisco
• D. hydrogenase
• E. nitrogenase

Answer: (E)

Verified step by step guidance

1. Understand the process of nitrogen fixation, which is the conversion of atmospheric nitrogen (N₂) into ammonia (NH₃). This is a crucial process for incorporating nitrogen into biological systems.
2. Identify the role of enzymes in biological reactions. Enzymes are proteins that act as catalysts to speed up chemical reactions without being consumed in the process.
3. Recognize that the enzyme complex responsible for nitrogen fixation is called nitrogenase. This enzyme is unique in its ability to break the strong triple bond of atmospheric nitrogen molecules.
4. Differentiate nitrogenase from other enzymes and proteins mentioned: Rhizobium is a genus of bacteria that often forms symbiotic relationships with legumes to fix nitrogen, leghemoglobin is a protein that helps regulate oxygen levels in root nodules, rubisco is an enzyme involved in the Calvin cycle of photosynthesis, and hydrogenase is an enzyme that catalyzes the reversible oxidation of molecular hydrogen.
5. Conclude that nitrogenase is the correct enzyme complex that catalyzes the conversion of atmospheric nitrogen to ammonia, as it directly facilitates the nitrogen fixation process.