The flowchart summarises the polymerase chain reaction. This reaction is used to amplify DNA



At the end of one cycle, two molecules of DNA have been produced from each original molecule.

How many DNA molecules will have been produced from one molecule of DNA after 4 complete cycles


(ii) State the enzyme meant by "the appropriate enzyme" in step 1. and explain why a specialised form of this enzyme is required for PCR


(iii) The seperation of the DNA strands (step 2.) is normally caused by the enzyme helicase, explain what causes the strands to separate in PCR



Suggest one use of the PCR technique