Q.Describe the nutritional classification of bacteria based on their source of energy and carbon.

[!TLDR]

The question asks how bacteria are classified nutritionally by their energy and carbon sources. …

Every bacterium needs a source of energy and a source of carbon to grow, and bacteria are grouped nutritionally according to where each comes from. Based on energy source, a bacterium is phototrophic if it obtains its energy from light, or chemotrophic if it obtains energy from chemical reactions. Based on carbon source, a bacterium is autotrophic if it builds its own organic molecules starting from carbon dioxide, or heterotrophic if it obtains carbon from ready-made organic compounds produced by other organisms. Combining the two criteria gives the four recognised nutritional groups: photoautotrophs (light energy, CO2 as carbon source), photoheterotrophs (light energy, organic carbon source), chemoautotrophs (chemical energy, CO2 a …

• Treating 'autotroph/heterotroph' and 'phototroph/chemotroph' as describing the same axis of classification rather than two independent criteria (carbon source vs energy source) that combine. …