1. What were the historical limitations of previous classification systems that led to and are solved by the three domain system that is use today?

2. Why is the gene coding for ribosomal RNA (rRNA) used for establishing phylogenetic relationships and how does this compare to previous methods for placing organisms in appropriate taxa?

3. What are the factors that limit our ability to fully classify and understand microbial diversity and what implications do these challenges have for environmental and health management. 
Additional Requirements 

Min Pages: 1 
Max Pages: 2 
Level of Detail: Show all work 
Other Requirements: Each question need to be answered with at least 150 words.