Recent work in classification of life on Earth has shown that what were once called prokaryotes are much more diverse than ever suspected. The prokaryotae are now divided into two domains, the Eubacteria and the Archaeabacteria, as different from each other as either is from the Eukaryota. No one of these groups is ancestral to the others, and each shares certain features with the others as well as having its own unique characteristics. One group of prokaryotae, the blue-green algae, have left a fossil record that is dated to be nearly 3.5 billion years old, among the oldest fossils currently known. These blue-green algae had cell walls and were photosynthetic. Considering this, where would you place the cyanobacteria in this cladogram?
A) archaebacteria
B) eubacteria
C) plantae
D) protista

Answer: archaebacteria

Archaebacteria is the kingdom of organisms that are very primitive. They do have separate type of metabolism, and mechanisms of producing food by themselves. Blue green algae is the type of bacteria which is the although self producing but its not matching with the characteristics of the other archaebacteria.

Archaebacteria has a specific type of cell wall which is not present in blue green algae. The mechanism of metabolism is also different. So its not a archaebacteria. So it’s a eubacteria.