Early classification systems only used observable features to place organisms into groups. Why is this not used now?

Classification systems are now based on observable features along with....

What does gathering molecular evidence involve?

Complete the sentences:
New technologies (e.g. new DNA _______ techniques, better _________) can result in new ______________ being made. How organisms are classified is continually ________ to take account of any new findings that scientists discover.

What has now replaced the five kingdom classification system?

What is the three domain classification system?

Why were the Prokaryotae reclassified into two domains?

What was the new evidence that supported the three domain system?