How did the presence of cyanobacteria on Earth in the past enable the later appearance of more advanced life-forms, such as humans?
A) They absorbed harmful chemicals, making the air safer.
B) They initiated the oxygenation of the atmosphere.
C) They fertilized the soil to let plants grow.
D) They increased the carbon dioxide in the atmosphere, causing the greenhouse effect.
E) They "ate" plants, creating the first digestive systems on Earth.

Question

Quizplus · Accepted Answer

Cyanobacteria were crucial in the Great Oxygenation Event, where they produced oxygen through photosynthesis, significantly increasing atmospheric oxygen levels and enabling the evolution of aerobic organisms, including more complex life forms.

How Did the Presence of Cyanobacteria on Earth in the Past