Figure 10.1
-Some photosynthetic bacteria (e.g., purple sulfur bacteria)have photosystem I but not II, while others (e.g. cyanobacteria)have both PSI and PSII. Which of the following might this observation imply?

Question

Figure 10.1 
-Some photosynthetic bacteria (e.g., purple sulfur bacteria)have photosystem I but not II, while others (e.g. cyanobacteria)have both PSI and PSII. Which of the following might this observation imply?

Quizplus · Accepted Answer

The fact that some bacteria only have PSI while others have both PSI and PSII suggests that PSI may be more ancestral and that PSII evolved later on. This could be because PSI evolved earlier as the first type of photosystem, and then PSII arose through gene duplication and mutation, allowing for more complex phototrophic capabilities.

Figure 10.1 -Some Photosynthetic Bacteria (E.g., Purple Sulfur Bacteria)have Photosystem I but Photosystem