How does inorganic nitrogen from the atmosphere
(N2) get into living systems?

When an organism excretes or dies, nitrogen is in the form of organic nitrogen in its tissues (e.g. amino acids, DNA). During the ammonification process, many fungi and prokaryotes then break the tissue down and release inorganic Nitrogen into the atmosphere as ammonia.

Explanation:

Plants use their roots for nitrogen compounds. When they consume the seeds, animals acquire certain chemicals. When plants and livestock die, or animals excrete waste, the organic nitrogen compounds return to the soil, where microorganisms known as decomposers break down their compounds.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.