Some photosynthetic bacteria (e.g., purple sulfur bacteria) have only photosystem I, whereas others (e.g., cyanobacteria) have both photosystem I and photosystem II. Which of the following might this observation imply?
A) Photosystem II was selected against in some species.
B) Photosynthesis with only photosystem I is more ancestral.
C) Photosystem II may have evolved to be more photoprotective.
D) Linear electron flow is more primitive than cyclic flow of electrons.
E) Cyclic flow is more necessary than linear electron flow.
Escherichia coli bacteria E. coli
Bacteria Joke
Periods of Purple Crying
Biosynthetic Families of Amino Acids in Bacteria and Plants
Pathways of nitrogen metabolism (purple) in the general pattern of intermediary metabolism
The DNA of S-type bacteria can transform R-type bacteria into the same S type.