When an organism encounters nitrate in its environment, which condition will determine whether the nitrate is used in an assimilatory or dissimilatory manner? a. low concentration or ammonia
b. low concentration of sulfate
c. oxygen present
d. low temperature
e. oxygen absent
f. high concentration of nitrite

Dissimilatory- oxygen absent

Assimilatory- high concentration of nitrite

Explanation:

In assimilatory nitrate reduction, ammonium is produced and subsequently incorporated into biomass to build up e.g., proteins and nucleic acids. Dissimilatory nitrate reduction is a process for energy conservation, in which nitrate is used as an electron acceptor in the (near) absence of oxygen . Dissimilatory nitrate reduction and nitrate storage in particular are physiological life traits that provide microbes with environmental flexibility (i.e., metabolic activity under both oxic and anoxic conditions) and resource independence (i.e., anaerobic metabolism without immediate nitrate supply), respectively. Such life traits are especially important in environments that are temporarily anoxic and/or nitrate-free and they may have developed as a “life strategy” in both prokaryotes and eukaryotes

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