What are the possible ways of obtaining and using energy by bacteria and briefly reveal their biological meaning?

1) Phototroph bacteria. These are blue-green algae containing chlorophyll in their cells and capable of photosynthesis.
2) Chemotroph bacteria. Convert the energy of inorganic compounds to create their own organic substances.
3) Heterotroph bacteria using organic compounds of dead or living bodies (parasites and saprophytes).

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