Most of the present-day atmospheric oxygen is thought to have been formed by the activity of ______?

سوچا جاتا ہے کہ موجودہ دور کے زیادہ تر ماحولیاتی آکسیجن ______ کی سرگرمی سے تشکیل پائے ہیں؟

Answer: Blue-green algae

Blue-green algae (Cyanobacteria) were among the first organisms to perform oxygenic photosynthesis, releasing oxygen into the atmosphere.

This process led to the Great Oxygenation Event.

It significantly increasing Earth's oxygen levels.

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