The term "ecological niche" encompasses both the habitat of an organism—essentially the physical space it occupies—and its functional role within the ecosystem, including its interactions with other organisms and its contributions to energy flow and nutrient cycling. In the context of UPSC Prelims GS Paper I, understanding ecological niches is crucial as they illustrate the complex interdependencies in ecosystems, highlighting how biodiversity influences ecological stability and resilience, thus reflecting critical environmental concepts emphasized in NCERT and other standard reference materials.