Question

Which organism performs oxygenic photosynthesis?

• A. \( \text{Purple bacteria} \)
• B. \( \text{Cyanobacteria} \)
• C. \( \text{Methanogens} \)
• D. \( \text{Green Sulphur bacteria} \)

Hint:

Cyanobacteria are often incorrectly called "Blue-Green Algae," but they are actually bacteria (prokaryotes), not true algae (eukaryotes).

Answer 1

The Correct Option is B

Concept: Photosynthesis can be classified based on whether oxygen is released as a byproduct.
• Oxygenic photosynthesis uses water (\(H_2O\)) as an electron donor, releasing Oxygen (\(O_2\)).
• Anoxygenic photosynthesis uses other molecules like \(H_2S\) and does not release oxygen.

Step 1: Identifying the Oxygen Producers.
Plants, algae, and a specific group of prokaryotes called Cyanobacteria perform oxygenic photosynthesis. Cyanobacteria were the first organisms on Earth to evolve this process, leading to the "Great Oxidation Event."

Step 2: Comparing with Anoxygenic Bacteria.
Purple bacteria and Green Sulphur bacteria perform anoxygenic photosynthesis and thrive in low-oxygen environments. Methanogens are archaea that produce methane and are not photosynthetic. Final Answer: Cyanobacteria is the organism listed that performs oxygenic photosynthesis.