Question

Arrange the steps in the nitrogen cycle in the correct order: biosphere, dead organic matter, nitrogen fixation, denitrification, ammonification, nitrification yielding nitrate, nitrification yielding nitrite.

Answer 1

The correct sequence of the nitrogen cycle starts with nitrogen fixation, followed by ammonification, nitrification yielding nitrite, nitrification yielding nitrate, assimilation into the biosphere, and concludes with denitrification. This cycle plays a vital role in the ecosystem, and microorganisms are key players in each step.

Step-by-step explanation:

The nitrogen cycle is a crucial ecosystem process in which nitrogen is converted between various chemical forms. The correct order of steps in the nitrogen cycle and their definitions are as follows:

1. Nitrogen fixation: Atmospheric nitrogen (N2) is converted into ammonia (NH3) by nitrogen-fixing bacteria, making it available for use by plants.
2. Ammonification: The conversion of nitrogenous waste and dead organic matter into ammonia by decomposing bacteria and fungi. This ammonia can then be used by plants or further processed by nitrifying bacteria.
3. Nitrification yielding nitrite: Ammonia is oxidized to nitrite (NO2-) by nitrifying bacteria such as Nitrosomonas.
4. Nitrification yielding nitrate: Nitrite is further oxidized to nitrate (NO3-) by similar nitrifying bacteria.
5. Assimilation into the biosphere: Plants absorb nitrates and ammonium and incorporate them into organic compounds. This is how nitrogen enters the biosphere and becomes part of the living organisms.
6. Denitrification: Soil bacteria convert nitrates back into gaseous nitrogen (N2), which reenters the atmosphere, completing the cycle.

Organic nitrogen in the ecosystem is cycled through these steps, playing a vital role in keeping the biosphere functioning. Microorganisms are integral to all four steps: fixation, ammonification, nitrification, and denitrification.