1.1. Fig. 1 below shows the polymerase chain reaction (PCR).

Fig. 1

State the purpose of PCR.

1.2. State and explain the purpose of the following molecules/substances in the thermocycler shown in Fig. 1.

(i) Primers

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(ii) Buffer solution

[1]

(iii) Free DNA nucleotides

[1]

1.3. Describe and explain the events taking place at the point marked X in Fig. 1.

1.4. Taq polymerase is a DNA polymerase enzyme usually found in the cells of the thermophilic bacterium Thermus aquaticus.

State why Taq polymerase is used in the elongation stage of the PCR cycle rather than human DNA polymerase.