Final answer:
Most algae get energy from sunlight, utilizing photosynthesis to create organic compounds. Algae are photoautotrophs and play a vital role in both aquatic ecosystems and the production of renewable fuels.
Step-by-step explanation:
Most algae get energy from sunlight. Algae are a type of photoautotroph, organisms that use energy from sunlight to synthesize their organic compounds via photosynthesis. This process involves converting sunlight and carbon dioxide into energy-rich compounds like sugars and oils, which can also be transformed into renewable fuels. Major examples of photoautotrophs include plants, algae, cyanobacteria, and some protists. Unlike plants that grow in soil, algae are primarily aquatic and can grow in both freshwater and saltwater environments. These organisms play a crucial role in aquatic ecosystems and contribute to the production of oxygen, serving as the basis for most aquatic food webs.