Final answer:
Cyanobacteria aided the evolution of complex life on land by producing oxygen and possibly giving rise to chloroplasts in plant cells. They continue to contribute to ecosystems through oxygen production and nitrogen fixation.
Step-by-step explanation:
Cyanobacteria, also known as blue-green algae, played a crucial role in the evolution of complex life on land. One of the significant contributions of cyanobacteria was their ability to produce oxygen through photosynthesis. This process led to the oxygenation of the Earth's atmosphere, creating an environment suitable for the evolution of other life forms. Cyanobacteria also likely gave rise to the chloroplasts found in plant cells, which allowed for efficient photosynthesis in plants.
In the present day, cyanobacteria continue to play a vital role in ecosystems. They are significant in aquatic environments, where they contribute to the production of oxygen and fix nitrogen, which is essential for plant growth. Additionally, cyanobacteria can form symbiotic relationships with plants, providing them with fixed nitrogen.
In conclusion, cyanobacteria were instrumental in aiding the evolution of complex life on land through oxygen production and the development of chloroplasts. While their significance may have waned compared to the Precambrian era, cyanobacteria still play an important role in maintaining the balance of ecosystems.