Material cycles and decomposition

During the decomposition of organic matter in a compost heap, saprobiontic microorganisms convert complex nitrogenous compounds into inorganic forms.

Which of the following describes the correct pathway and conversion mediated by these saprobionts?

Reduction of dissolved nitrate ions ( $NO_3^-$ ) to gaseous dinitrogen ( $N_2$ ) under anaerobic conditions.

Extracellular hydrolysis of polypeptides to amino acids, followed by intracellular deamination to produce ammonium ions ( $NH_4^+$ ).

Chemoautotrophic oxidation of ammonium ions ( $NH_4^+$ ) to nitrite ions ( $NO_2^-$ ) to obtain energy.

Symbiotic reduction of atmospheric nitrogen ( $N_2$ ) to ammonia ( $NH_3$ ) using ATP supplied by a host plant.

Material cycles and decomposition Questions

During the decomposition of organic matter in a compost heap, saprobiontic microorganisms convert complex nitrogenous compounds into inorganic forms.

Which of the following describes the correct pathway and conversion mediated by these saprobionts?

Reduction of dissolved nitrate ions ( $NO_3^-$ ) to gaseous dinitrogen ( $N_2$ ) under anaerobic conditions.

Extracellular hydrolysis of polypeptides to amino acids, followed by intracellular deamination to produce ammonium ions ( $NH_4^+$ ).

Chemoautotrophic oxidation of ammonium ions ( $NH_4^+$ ) to nitrite ions ( $NO_2^-$ ) to obtain energy.

Symbiotic reduction of atmospheric nitrogen ( $N_2$ ) to ammonia ( $NH_3$ ) using ATP supplied by a host plant.