Ch 10: Photosynthesis The Process That Feeds the Biosphere Photosynthesis is the process that converts solar energy into chemical energy Directly or indirectly, photosynthesis nourishes almost the entire living world Autotrophs sustain themselves without eating anything derived from other organisms Autotrophs are the producers of the biosphere, producing organic molecules from CO2 and other inorganic molecules (fixing carbon) Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecules Photosynthesis occurs in plants, algae, certain other protists, and some prokaryotes Heterotrophs obtain their organic material from other organisms Heterotrophs are the consumers of the biosphere