Final answer:
A chemosynthetic autotroph produces energy-rich organic compounds from energy-poor inorganic substances, using chemical reactions instead of sunlight, like those found in deep-sea hydrothermal vent ecosystems.
Step-by-step explanation:
A chemosynthetic autotroph would make its living by combining energy-poor inorganic compounds with an energy-rich inorganic compound to produce an energy-rich organic compound and energy-poor by-products. Unlike photosynthetic autotrophs, which use solar energy, chemoautotrophs derive energy from chemical reactions often involving substances like hydrogen sulfide or methane. These organisms play a critical role in unique ecosystems such as those found in hydrothermal vents, where light is not available, by acting as primary producers and supporting a diverse array of life.