Which term describes organisms that use light as their energy source to synthesize organic substances?

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

Answer: (A)

The concept here is how organisms obtain energy to build organic molecules. Organisms that use light as their energy source to synthesize organic substances are photoautotrophs. They capture light through photosynthesis and convert carbon dioxide into organic matter, which they then use to grow. This role makes them primary producers in ecosystems, laying the foundation for food webs.

Heterotrophs, by contrast, rely on consuming already-made organic molecules from other organisms for both carbon and energy. Chemoautotrophs do autotrophy too, but they derive their energy from chemical reactions involving inorganic substances rather than from light. Habitat isn’t about how energy is obtained or how organic matter is synthesized.