In the evolutionary history of life on Earth, which group of organisms is thought to have evolved oxygenic photosynthesis first?

• A. Fungi
• B. Green algae
• C. Land plants
• D. Cyanobacteria

Answer: (D)

Verified step by step guidance

1. Understand the concept of oxygenic photosynthesis: it is the process by which certain organisms use light energy to convert carbon dioxide and water into glucose and oxygen, releasing oxygen as a byproduct.
2. Recall that oxygenic photosynthesis is a key evolutionary development that led to the accumulation of oxygen in Earth's atmosphere, enabling aerobic life forms to evolve.
3. Identify the groups listed: Fungi, Green algae, Land plants, and Cyanobacteria, and consider their evolutionary timeline and characteristics related to photosynthesis.
4. Recognize that Cyanobacteria are prokaryotic organisms known as the first to perform oxygenic photosynthesis, significantly contributing to the Great Oxygenation Event.
5. Conclude that among the options, Cyanobacteria evolved oxygenic photosynthesis first, before the appearance of green algae and land plants, which are eukaryotic and evolved later.