What is the ability of the environment to meet human needs indefinitely called?

The answer is; sustainability.

This means using resources while minding the time required for these resources to be replenished. Resources that need a long time to replenish are used sparingly. This way these resources can last long enough to be used even by future human generations.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.