Which statement about autotrophs' carbon source is true?

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Multiple Choice

Which statement about autotrophs' carbon source is true?

Autotrophs build their own organic matter from inorganic carbon, not from preformed organic molecules. They take carbon dioxide and convert it into sugars and other organic compounds using energy from light (for photoautotrophs) or from chemical reactions (for chemoautotrophs). This ability to fix CO2 is what lets autotrophs sustain themselves without ingesting organic carbon from the environment. Organic carbon would imply they rely on other organisms for carbon, which is the hallmark of heterotrophs, not autotrophs. Water isn’t a carbon source either; it may participate in reactions and provide electrons in some processes, but it does not supply carbon for biosynthesis. So the true carbon source for autotrophs is carbon dioxide.

Autotrophs build their own organic matter from inorganic carbon, not from preformed organic molecules. They take carbon dioxide and convert it into sugars and other organic compounds using energy from light (for photoautotrophs) or from chemical reactions (for chemoautotrophs). This ability to fix CO2 is what lets autotrophs sustain themselves without ingesting organic carbon from the environment.

Organic carbon would imply they rely on other organisms for carbon, which is the hallmark of heterotrophs, not autotrophs. Water isn’t a carbon source either; it may participate in reactions and provide electrons in some processes, but it does not supply carbon for biosynthesis. So the true carbon source for autotrophs is carbon dioxide.

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