Saprobionts (decomposers) play a key role in material cycles by breaking down organic matter. Which of the following options correctly describes the specific role and mechanism of saprobionts during the nitrogen cycle?
They absorb ammonium ions (NH4+NH_4^+NH4+) from the soil and oxidise them to nitrite ions (NO2−NO_2^-NO2−) to generate metabolic energy.
They secrete extracellular enzymes to hydrolyse nitrogen-containing organic compounds in dead matter, releasing ammonium ions (NH4+NH_4^+NH4+) into the soil.
They use nitrate ions (NO3−NO_3^-NO3−) as terminal electron acceptors in anaerobic respiration, reducing them to nitrogen gas (N2N_2N2).
They form mutualistic relationships with plant roots to convert atmospheric nitrogen gas (N2N_2N2) directly into organic amino acids.
