Which organisms were the earliest oxygen-producing life-forms in the context of organic chemistry?

• A. Fungi
• B. Algae
• C. Protozoa
• D. Cyanobacteria

Answer: (D)

Verified step by step guidance

1. Understand the context: The question is about the earliest oxygen-producing organisms, which is a key concept in the study of the Earth's early atmosphere and the evolution of life.
2. Identify the role of oxygen production: Oxygen production is primarily associated with the process of photosynthesis, where organisms convert carbon dioxide and water into glucose and oxygen using sunlight.
3. Recognize the organisms involved in early photosynthesis: Cyanobacteria are known as the earliest organisms capable of photosynthesis, significantly contributing to the oxygenation of Earth's atmosphere.
4. Differentiate between the options: Fungi, algae, and protozoa are not the earliest oxygen producers. Fungi do not perform photosynthesis, protozoa are primarily heterotrophic, and algae evolved later.
5. Conclude with the correct organism: Cyanobacteria, also known as blue-green algae, were the first to perform oxygenic photosynthesis, leading to the Great Oxygenation Event.