Question the first:
A long time ago I was struck by the similarity of hemoglobin and chlorophyll, and I have always wondered if there was some evolutionary connection.
So is there a connection? Some similarity in the DNA that codes for them?
Question the second:
When I learned of molluscs, arthropods, and assorted deep sea invertibrates having blue blood, I thought: replace the iron with copper, no suprise.
Now in an answer to another question on this site I discover that blue blooded creatures use hemocyanins. I look up hemocyanins and discover that they are polymers of histidine peptides, not similar at all.
So I research hemoglobin and chlorophyll and discover: there are whole families of them, and that they are porphyrins.
Now porphyrins with iron are hemes, and there are may of them, porphyrins with magnesium are chlorins, lots of those too, but apparently there are porphyrins with copper, cobalt, nickel, and zinc.
So what biological functions are performed by the porphyrins with copper, cobalt, nickel, and zinc?