Energy flow in an ecosystem follows the unidirectional transfer of energy from the sun to producers and then to consumers.
Key steps in energy flow:
Diagram:

| List I | List II |
|---|---|
| A. The Evil Quartet | III. Causes of biodiversity losses |
| B. Ex situ conservation | I. Cryopreservation |
| C. Lantana camara | II. Alien species invasion |
| D. Dodo | IV. Extinction |