Energy in most ecosystems must flow through autotrophs because ______.

• A. autotrophs are the only organisms that decompose organic matter
• B. autotrophs convert solar energy into chemical energy through photosynthesis
• C. autotrophs release energy by breaking down dead organisms
• D. autotrophs consume other organisms to obtain energy

Answer: (B)

Verified step by step guidance

1. Understand the role of autotrophs in ecosystems: Autotrophs are organisms that can produce their own food using light (via photosynthesis) or chemical energy (via chemosynthesis). They are also known as primary producers because they form the base of the food chain.
2. Recognize the process of photosynthesis: Autotrophs, such as plants, algae, and some bacteria, use sunlight to convert carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂). This process stores solar energy in the form of chemical energy.
3. Eliminate incorrect options: Autotrophs do not decompose organic matter (this is the role of decomposers like fungi and bacteria), nor do they consume other organisms for energy (this is the role of heterotrophs).
4. Identify the correct explanation: Autotrophs are essential because they convert solar energy into chemical energy, which is then available to other organisms in the ecosystem, such as herbivores and carnivores.
5. Conclude that energy in most ecosystems must flow through autotrophs because they are the primary source of chemical energy, which supports all other trophic levels in the food chain.