Which statement best describes energy flow in an ecosystem?

• A. The Sun directly powers all animal actions.
• B. Water provides all energy for producers.
• C. Photosynthesis is the process by which plants convert sunlight to chemical energy.
• D. Energy from the Sun is dissipated as heat with no transfer to organisms.

Answer: (C)

Energy in ecosystems starts with sunlight and is captured by producers. Plants, algae, and some bacteria use photosynthesis to change light energy into chemical energy stored in sugars. This stored chemical energy then passes through the food web when organisms eat plants or other organisms, providing the fuel for growth, movement, and life processes. That’s why describing photosynthesis as the process by which plants convert sunlight to chemical energy is the best answer.

The other ideas don’t fit as well. Sunlight isn’t used directly by animals for every action; energy for animals comes from the food they eat, which ultimately traces back to plants. Water isn’t the source of energy itself. And while some energy is eventually released as heat, energy is still transferred to organisms along the way as food is consumed, not just dissipated with no transfer.