Which microbe is exclusively autotrophic?

The choice of algae as exclusively autotrophic is accurate because algae are primarily photosynthetic organisms capable of converting sunlight into energy through the process of photosynthesis. They utilize chlorophyll and other pigments to absorb light energy, enabling them to synthesize organic compounds from carbon dioxide and water.

Unlike algae, bacteria represent a diverse group that includes autotrophic organisms, such as cyanobacteria, as well as heterotrophic bacteria that derive their food from organic sources. Fungi, on the other hand, are strictly heterotrophic, meaning they cannot perform photosynthesis and instead obtain nutrients by breaking down organic matter. Viruses are not considered living organisms as they cannot carry out metabolic processes or reproduce independently; they rely on host cells for replication and therefore cannot be classified as autotrophic or heterotrophic.

Thus, the uniqueness of algae lies in their exclusive ability to harness solar energy for growth and nourishment, distinguishing them as true autotrophs in the realm of microorganisms.