What is the ultimate source of energy for the ecosystems?

Explanation

**Step-by-Step Solution:**

1. **Understanding Ecosystems**: An ecosystem consists of living organisms interacting with each other and their physical environment. Energy flow is a crucial aspect of these interactions.

2. **Identifying the Source of Energy**: The primary source of energy for most ecosystems is the Sun. Solar radiation is captured by plants through a process called photosynthesis.

3. **Photosynthesis Process**: During photosynthesis, plants use sunlight, carbon dioxide, and water to produce glucose (a form of chemical energy) and oxygen. Chlorophyll in the plants is responsible for capturing sunlight.

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