Through which metabolic process does carbon enter the food web?

• A. Fermentation
• B. Cellular respiration
• C. Photosynthesis
• D. Glycolysis

Answer: (C)

Verified step by step guidance

1. Understand the food web: The food web represents the flow of energy and nutrients through ecosystems, starting with primary producers (plants, algae, and some bacteria) that convert inorganic carbon into organic molecules.
2. Identify the role of carbon: Carbon enters the food web as part of organic molecules, which are synthesized by primary producers during photosynthesis. These molecules are then consumed by other organisms in the food web.
3. Define photosynthesis: Photosynthesis is the metabolic process by which autotrophic organisms (like plants and algae) use sunlight, water, and carbon dioxide to produce glucose (C₆H₁₂O₆) and oxygen (O₂). The chemical equation for photosynthesis is: $6_{\mathrm{CO}}+6_H\to C_{6_H}$
4. Compare other processes: Fermentation, cellular respiration, and glycolysis are metabolic processes that occur in organisms to break down organic molecules for energy. These processes do not introduce carbon into the food web; instead, they utilize carbon already present in organic molecules.
5. Conclude the correct process: Photosynthesis is the only process listed that introduces carbon into the food web by converting inorganic carbon dioxide into organic molecules, which serve as the foundation for energy and nutrient flow in ecosystems.