What is a niche?

an organism’s living and nonliving interactions with its environment
an organism’s ability to interbreed with other organisms
an organism’s ability to reproduce asexually and produce organisms identical to itself

Option A, an organism’s living and nonliving interactions with its environment

Explanation:

The environment in which an organism habitat comprising of all its interaction with all biotic and abiotic factors is known as a niche. All organisms in an ecosystem acquire a niche which defines its role in the ecological system,  energy flow and recycling of nutrients. It also include the type of relationship an organism in an ecosystem have with all other organisms such as parasitic, mutualistic, etc.

Option A

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure