Which of the following represents the correct hierarchical organization of life from the smallest to the largest scale?

Step 1: Analyze the question You are asked to arrange levels of biological organization from smallest to largest. Only one option has every level in the right order.

Step 2: The concept Life is organized in increasing complexity:

1. Cell: the basic unit of life
2. Tissue: a group of similar cells doing the same job (e.g. muscle tissue)
3. Organ: different tissues working together (e.g. the heart)
4. Organ system (sometimes included): organs working together (e.g. the circulatory system)
5. Organism: a complete living individual
6. Population: organisms of the same species living in one area
7. Community: all the different populations living in an area
8. Ecosystem: the community plus its non-living environment (soil, water, climate)

Step 3: Check each option

• A: Starts with organs, then tissues, then cells. This is reversed, so it is wrong.
• B: Puts organs before tissues. Tissues are smaller than organs, so it is wrong.
• C: Puts tissues before cells. A cell is smaller than a tissue, so it is wrong.
• D: Cells → tissues → organs → organisms → populations → communities → ecosystems. Every step is in the correct order. ✔

Step 4: Answer The correct option is D.

Exam tip: Use the memory chain "Can The Old Of Pa Come Early?", which stands for Cell, Tissue, Organ, Organism, Population, Community, Ecosystem. In questions like this, find the first level that is out of place (such as organs before cells) and eliminate that option immediately.