If you find a new organism in a pond, what features will you observe to classify it and why?
To classify a new organism, I will observe its external features (shape, size, body organisation), mode of nutrition (autotrophic or heterotrophic), and cell structure (unicellular or multicellular, prokaryote or eukaryote, presence or absence of cell wall). I will also examine its internal structures, ecological role, and methods of reproduction.
These features are observed because they help in understanding the similarities and differences among organisms. Similar features in organisms suggest that they have evolved from common ancestors. Using these characteristics provides a systematic way of organising the Earth's living diversity, known as classification, ensuring the organism is grouped accurately rather than just by habitat.
Explanation
The textbook context explicitly lists the criteria scientists use to classify living organisms: external features, mode of nutrition, internal structures, cell structure, ecological role, reproduction, and genetic similarity. The 'why' is also directly addressed in the text, which states that these features help understand similarities and differences, and that similar features suggest evolution from common ancestors, allowing for systematic classification of living diversity.