Organisms that use light as a source of energy to synthesize organic substances are known as what?

• A. Heterotrophs
• B. Photoautotrophs
• C. Chemoautotrophs
• D. Habitat

Answer: (B)

Using light to drive the synthesis of organic molecules is the hallmark of photoautotrophs. They capture light energy to power photosynthesis, converting carbon dioxide into organic compounds like sugars that the organism can build into biomass. This group includes plants, algae, and cyanobacteria, which form the base of most ecosystems by providing organic matter and releasing oxygen as a byproduct. The contrast is with heterotrophs, which obtain energy and carbon from already-made organic molecules; chemoautotrophs, which fix carbon using energy from chemical reactions rather than light; and habitat, which is not a metabolic mode.