6.01: classification of living organisms 1. explain the linnaean system of classification. what has caused changes to this system since the early 1700s? 2. what are the categories for the linnaean system? which is the most specific? which is the most broad? 3. explain the domain system. how has it changed over the years? 4. how are gene and protein sequences used to classify organisms? 5. explain why viruses are considered nonliving. 6. compare and contrast viruses and bacteria. 7. make sure you understand phylogeny and cladograms.