Title: Bacteria.
Question: Green sulfur-bacteria is typical representative of what type of bacteria?

Title: Roman Republic.
Question: During what century were reformed passed that allowed laws passed by the plebeians to have the full force of the law?

Title: Group (mathematics).
Question: Where did the idea of a group come from?

Title: Ann Arbor, Michigan.
Question:
What percentage makes up for the whites living in the city?