It has been suggested that cyanobacteria are the most important organisms to have evolved on the Earth. What evidence justifies this view?
A)Some cyanobacteria can fix nitrogen (which plants need in order to produce oxygen), making them unique among bacteria.
B)Some cyanobacteria differentiate to form multiple cell types, making them the ancestors of plants and animals.
C)Cyanobacteria evolved the ability to use water as an electron donor in photosynthesis, generating the oxygen gas found in the atmosphere.
D)Cyanobacteria form microbial mats, enabling them to spread across lake bottoms and shallow seafloors.

Question

Quizplus · Accepted Answer

Cyanobacteria are responsible for the oxygenation of Earth's atmosphere through the evolution of photosynthesis, specifically through their ability to use water as an electron donor in photosynthesis. This allowed for the accumulation of oxygen gas in the atmosphere, which enabled the evolution of aerobic organisms. While the other options are also important characteristics of cyanobacteria, the ability to produce oxygen is the most significant and transformative.

It Has Been Suggested That Cyanobacteria Are the Most Important