Only Certain Prokaryotes Can Perform Nitrogen Fixation, but Nitrogen-Fixing Prokaryotes

question 61

Multiple Choice

Only certain prokaryotes can perform nitrogen fixation, but nitrogen-fixing prokaryotes are not known to live inside animals. Thus, how do animals gain access to fixed nitrogen?

• A)They may breathe it in from air that has experienced lightning discharges.
• B)They may ingest nitrogen fixers.
• C)They may ingest plants that harbor nitrogen fixers, or plants that absorbed fixed nitrogen from the soil.
• D)They may ingest other animals that had done either (B)or (C)above.
• E)Answers (B), (C), and (D)above are all possible.

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