Which of these answers illustrates a major difference between oxygenic and anoxygenic photosynthesis?

• A. Oxygenic photosynthesis uses H₂O as the electron donor, while anoxygenic photosynthesis uses H₂S.
• B. Oxygenic photosynthesis produces O₂ gas, while anoxygenic photosynthesis produces elemental sulfur.
• C. Oxygenic photosynthesis uses PSI & PSII, while anoxygenic photosynthesis uses PSI or PSII.
• D. Oxygenic photosynthesis uses chlorophyll-a to absorb light, anoxygenic photosynthesis uses bacterio-chlorophylls.
• E. All of the above are major differences between oxygenic and anoxygenic photosynthesis.

Answer: (E)

Verified step by step guidance

1. Understand the basic concept of photosynthesis, which is the process by which light energy is converted into chemical energy by organisms.
2. Recognize that oxygenic photosynthesis is the type of photosynthesis that occurs in plants, algae, and cyanobacteria, where water (H2O) is used as the electron donor, and oxygen (O2) is produced as a byproduct.
3. Identify that anoxygenic photosynthesis occurs in certain bacteria, such as purple and green sulfur bacteria, where hydrogen sulfide (H2S) is used as the electron donor, and elemental sulfur or sulfate is produced instead of oxygen.
4. Note the difference in the photosystems used: oxygenic photosynthesis involves both Photosystem I (PSI) and Photosystem II (PSII), while anoxygenic photosynthesis typically involves only one of these systems.
5. Understand the difference in pigments: oxygenic photosynthesis uses chlorophyll-a to capture light energy, whereas anoxygenic photosynthesis uses bacteriochlorophylls, which are adapted to absorb light at different wavelengths.