Question

Are bacteria autotrophic or heterotrophic?

Answer 1

Autotrophic organisms:

1. Autotrophic organisms possess specialised pigments that help them to synthesize their own food from inorganic substances such as CO₂, H₂O, minerals, etc.
2. These primary producers use inorganic sources of carbon.
3. Example: plants, algae.

Heterotrophic organisms:

1. Heterotrophic organisms depend on other organisms for deriving nutrition.
2. They belong to secondary and tertiary levels in the food chain that use organic carbon sources.
3. Example: fungi, animals.

Bacteria:

1. Bacteria are prokaryotes. They are unicellular organisms that lack a true nucleus and membrane-bound cell organelles.
2. Bacteria can be both autotrophic and heterotrophic.
3. Autotrophic bacteria such as Cyanobacteria and Rhodospirillum contain pigment-containing vesicles called ‘chromatophores’.
4. These vesicles contain carotenoids and bacteriochlorophyll that help in photosynthesis.
5. Heterotrophic bacteria can be parasitic, saprophytic, or symbiotic.
6. Parasitic bacteria (e.g., Salmonella) obtain nutrition from living organisms.
7. Saprophytic bacteria (e.g., Pseudomonas) rely on dead organic matter for nutrition.
8. Symbiotic bacteria (e.g., Rhizobium) live in the root nodules of certain plants and receive nutrients from the plant.