What is the primary source of energy in a food chain?

• A. Oxygen
• B. Carbon dioxide
• C. Water
• D. Sun

Answer: (D)

Verified step by step guidance

1. Understand the concept of a food chain: A food chain represents the flow of energy through different organisms in an ecosystem, starting from producers (plants) to consumers (herbivores, carnivores, etc.).
2. Recognize the role of producers: Producers, such as plants, are the foundation of the food chain. They use energy from the environment to create food through photosynthesis.
3. Identify the energy source for photosynthesis: Plants use sunlight as the primary energy source to convert carbon dioxide and water into glucose and oxygen. This process is represented by the equation: $C_6{H}_{12}{O}_6+6O=6\mathrm{CO}+6H2O$.
4. Explain why sunlight is the primary energy source: Sunlight provides the energy needed for photosynthesis, which is the process that supports all life in the food chain by producing food and oxygen.
5. Conclude that the Sun is the correct answer: The Sun is the ultimate source of energy for all ecosystems, as it drives the process of photosynthesis and sustains the food chain.