Here's why:
* Photosynthesis: Algae contain chlorophyll, the pigment that allows them to capture sunlight and convert it into energy through photosynthesis. They are essentially the primary producers in many aquatic ecosystems.
* Lack of Other Nutritional Modes: Unlike some other protists, algae do not have the ability to ingest food particles (heterotrophic) or absorb nutrients from their surroundings (saprophytic). Their sole source of nutrition is photosynthesis.
Let me know if you have any more questions about protists or photosynthesis!
