Which molecule would be the most affected by limited nitrogen

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

for example, no new evidence will demonstrate that the earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the earth is not divided into solid plates that have moved over geological timescales .