The population of different organisms that exist together in a habitat is called

1. Analyze the question The question asks for the term describing populations of different organisms living together in a habitat. The key phrases are "populations of different organisms" and "together in a habitat."

2. Explain the concept Ecology uses a hierarchy of levels of organization:

• Individual: a single organism
• Population: a group of the same species living in one area
• Community: all the different populations (plants, animals, microbes) living and interacting in the same habitat
• Ecosystem: the community plus its non-living environment
• Biome: a large region defined by climate and dominant vegetation (e.g. the tropical rainforest or the Guinea savanna)
• Biosphere: all parts of the Earth where life exists

3. Solution, checking each option

• A. Biomes: these are large geographical zones, not a group of organisms in a habitat. Wrong.
• B. Biosphere: this is the whole life-supporting part of the Earth, far too broad. Wrong.
• C. Community: this means different populations living together and interacting in a habitat. Correct.
• D. Ecology: this is the study of the relationships between organisms and their environment, not a group of organisms. Wrong.

4. Answer The correct option is C. community.

5. Exam tip Remember the ladder: Individual → Population → Community → Ecosystem → Biome → Biosphere. "Community" is the step where different species first appear together. A population is always one species. Also, any option ending in "-ology" or "-ics" (like ecology) usually names a subject of study, not a group of living things.