Re: What kind of photosynthesis does algae use -C3, C4 or an other kind?

Mikkel,

Algae certainly have C3 photosynthesis.  The confusion over C4 
metabolism arises because the enzymes present in C4 photosynthesis are 
present in algae as well.  These enzymes, PEP carboxylase and PEP 
carboxykinase, supplement C3 metabolism in the algae.  These enzymes are 
present in different algal groups in different amounts and are not 
sensitive to oxygen like the Calvin cycle enzyme Ribulose bisphosphate 
carboxylase.  Unlike terrestrial plants, though, they do not have the 
specialized Kranz anatomy.  So algae are capable of more than C3 metabolism 
alone, but is not as complex as C4 or Crassulacean acid metabolism.