Organisms that use hydrogen sulfide or other chemicals as energy source instead of light are known as?

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

Answer: (D)

Organisms that get their energy from chemical reactions rather than from sunlight are chemoautotrophs. They use inorganic molecules like hydrogen sulfide as their energy source and fix carbon dioxide to build organic molecules, allowing them to thrive in environments without light, such as deep-sea vents. This is different from photoautotrophs, which rely on light energy to drive the synthesis of organic compounds, and from heterotrophs, which must consume already-made organic molecules. The term chemoautotrophs specifically describes the combination of chemical-energy use and carbon fixation, which is why it’s the best fit for organisms powered by chemical sources like hydrogen sulfide.