Which of the following best describes an ecosystem?

• A. All the living organisms on Earth considered together, excluding their physical environment
• B. A biological community of interacting organisms and their physical (abiotic) environment within a defined area
• C. All the populations of a single species living in the same area
• D. A group of different species that live in the same area but do not interact

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the term 'ecosystem' by breaking it down into its components: 'biotic' (living organisms) and 'abiotic' (non-living physical environment) factors.
2. Step 2: Recognize that an ecosystem includes both the biological community (all interacting living organisms) and their physical environment, which interact as a system.
3. Step 3: Compare the given options to see which one includes both living organisms and their physical environment interacting within a defined area.
4. Step 4: Eliminate options that mention only living organisms without their environment, or only a single species or non-interacting species.
5. Step 5: Conclude that the best description of an ecosystem is 'A biological community of interacting organisms and their physical (abiotic) environment within a defined area' because it encompasses both biotic and abiotic components and their interactions.