[Campbell Biology P.864] Based on the 'VISUAL SKILLS' question and the information presented... | Practice Question

Based on the 'VISUAL SKILLS' question and the information presented in Figure 37.11 and the text, if an animal died near a plant's root, which forms of nitrogen would the plant most likely have increased access to, and why?

  • A: Only ammonium (NH4+), because decomposers would convert organic material directly into this form.
  • B: Only nitrate (NO3-), because ammonium is quickly converted to nitrate by nitrifying bacteria.
  • C: Both ammonium (NH4+) and nitrate (NO3-), because ammonifying bacteria would produce ammonium from the dead animal, and nitrifying bacteria would then convert some of that ammonium to nitrate.
  • D: Neither, as dead organic matter needs to be processed into atmospheric N2 before plants can absorb it.

Explanation

The text explains that ammonification is the process where decomposers convert organic nitrogen from dead organic material into NH4+. Subsequently, nitrifying bacteria convert this NH4+ to NO2- and then to NO3-. Since plants can absorb both NH4+ some and primarily NO3-, the death of an animal would lead to an increased supply of both forms, which are made available through microbial activity.