5. We say that a good predator-prey relationship keeps the two
populations "in balance." What is meant by this?

It means that they keep each others' population regulated.

Explanation:

Without one or the other, ones' population would sky rocket and there would be too many in an unhealthy manner, or the other wouldn't be able to survive and their numbers would drop low.

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.