Which statement correctly describes a photoheterotroph?

• A. Energy: light; Carbon: organic compounds
• B. Energy: chemicals; Carbon: CO2
• C. Energy: light; Carbon: CO2
• D. Energy: chemicals; Carbon: organic compounds

Answer: (A)

The key idea is how the organism gets its energy and its carbon. A photoheterotroph uses light as the energy source to power metabolism (phototrophy) and relies on organic compounds from the environment as its carbon source (heterotrophy). This combination is distinct from others, such as using light for energy but CO2 as carbon (photoautotroph) or using chemicals for energy with inorganic CO2 for carbon (chemoautotroph), or using chemicals for energy with organic carbon (chemoheterotroph). So the best description is energy from light and carbon from organic compounds. Purple non-sulfur bacteria are classic examples that fit this lifestyle.