OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

How is each dome in the Eden Project considered a closed loop system?

1. All waste is completely eliminated within the dome

2. The output of organisms is used as input for other organisms

3. Only decomposing matter is cycled within the dome

4. There is no human interaction within the dome

The correct answer is: The output of organisms is used as input for other organisms

In the Eden Project, each dome operates as a closed loop system primarily because the outputs of one type of organism are utilized as inputs for other organisms, creating a self-sustaining environment. This ecological principle illustrates how energy and nutrients circulate within the ecosystem. For example, plants produce oxygen and organic matter through photosynthesis, which is then used by animals for respiration. The waste products from these animals, in turn, can serve as nutrients for the plants, thus maintaining balance and supporting various life forms. This interdependence ensures that resources are efficiently recycled, minimizing waste and maximally utilizing the available energy. The other choices do not accurately reflect the dynamics of a closed loop system in the Eden Project. While minimizing waste is a goal, it is not feasible for all waste to be completely eliminated, as some degree of waste is always produced in biological processes. Additionally, cycling matters does encompass decomposing material, but it also involves the entire nutrient cycle and energy flow, not just decomposition. Lastly, while human interaction is minimized to maintain natural processes, it still exists in the management of the system, which does not align with the definition of a closed loop system devoid of human influence.