An organism's particular role in its habitat, or when and how it survives is called its A. carrying capacity
B. ecosystem
C. competition
D. niche
This is a small fun quiz for anyone!

Niche

Explanation:

Ecosystem is a system of organisms. I forgot what a carrying capacity is but it's not related to survival. Competition doesn't show an organism's particular role in the ecosystem. Niche fits both of the criteria. For example, a Velociraptor fits the small predator niche in a Cretacious setting.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.