Which of the following types of organisms produces nearly all of the biosphere's food supply?

• A. Decomposers
• B. Parasites
• C. Chemoheterotrophs
• D. Photoautotrophs

Answer: (D)

Verified step by step guidance

1. Understand the role of photoautotrophs: Photoautotrophs are organisms that use light energy to synthesize organic compounds from carbon dioxide and water through the process of photosynthesis. These organic compounds serve as the primary food source for nearly all organisms in the biosphere.
2. Recognize the importance of photosynthesis: During photosynthesis, photoautotrophs convert light energy into chemical energy stored in glucose and other organic molecules. This process also releases oxygen as a byproduct, which is essential for aerobic organisms.
3. Identify examples of photoautotrophs: Common examples include plants, algae, and cyanobacteria. These organisms form the base of most food chains and are critical for supporting life on Earth.
4. Compare photoautotrophs to other types of organisms: Decomposers break down dead organic matter, parasites feed on living hosts, and chemoheterotrophs obtain energy by consuming organic compounds. None of these groups produce the biosphere's food supply on the same scale as photoautotrophs.
5. Conclude why photoautotrophs are the correct answer: Photoautotrophs are the primary producers in ecosystems, creating the organic matter that supports all other organisms either directly or indirectly. This makes them the key contributors to the biosphere's food supply.