The three steps of the nitrogen cycle in order, starting with nitrogen gas in the atmosphere, are

Question

Notification, nitrogen fixation, and dentirifiaction

Nitrogen fixation, nitrification, and nitrogen fixation

Nitrogen fixation, dentrifaction, and nitrification

Answer 1

The correct order of the three main steps of the nitrogen cycle, starting with nitrogen gas in the atmosphere, is nitrogen fixation, nitrification, and denitrification.

1. Nitrogen Fixation: This process converts nitrogen gas (N₂) in the atmosphere into ammonia (NH₃) or related compounds in the soil. This is done by certain bacteria and by lightning.

2. Nitrification: This is the process where ammonia is converted into nitrites (NO₂⁻) and then into nitrates (NO₃⁻) by nitrifying bacteria.

3. Denitrification: This is the process where nitrates are converted back into nitrogen gas (N₂) or nitrous oxide (N₂O), returning nitrogen to the atmosphere.

So the correct statement is: Nitrogen fixation, nitrification, and denitrification.