<span>The greatest concentration of nitrogen on the Earth is found in its atmosphere. The atmosphere is approximately 78 percent nitrogen. and second one bacteria</span>
I think I’ll go with C. long dry cold winters

<h2>Fixation</h2>
Nitrogen in its gaseous form (N2) can’t be used by most living things. It has to be converted or ‘fixed’ to a more usable form through a process called fixation. There are three ways nitrogen can be fixed to be useful for living things:
<h3>Biologically: </h3>
Nitrogen gas (N2) diffuses into the soil from the atmosphere, and species of bacteria convert this nitrogen to ammonium ions (NH4+), which can be used by plants. Legumes (such as clover and lupins) are often grown by farmers because they have nodules on their roots that contain nitrogen-fixing bacteria.
<h3>Through lightning: </h3>
Lightning converts atmospheric nitrogen into ammonia and nitrate (NO3) that enter soil with rainfall.

Here is what all 3 symbiotic relationships are: Parasitism is where one organism is benefited and the other is harmed. Commensalism one organism is benefited and the other one is not helped or harmed. Mutualism is were both organisms are benefited or both help each other. Easy ways to remember symbiotic relationships :)
Answer: . An organelle (think of it as a cell's internal organ) is a membrane bound structure found ... There are actually two different endoplasmic reticuli in a cell: the smooth ... which project into the extracellular space and act like a name tag for the cell.
Explanation: