(a(i))[2]
Explain the purpose of heating the DNA sample to $95^{\circ}\text{C}$ in step $1$.
(a(ii))[2]
Explain the role of primers in step $2$.
(a(iii))[2]
Explain the reason for using the enzyme $Taq$ polymerase in step 3.
(b(i))[2]
Explain why a cell usually contains more than 100 copies of mtDNA, but only two copies of nuclear DNA.
(b(ii))[1]
Because all of the mitochondria in a zygote are supplied by the egg rather than the sperm, list the letters of the people in the family tree in Fig. 3.2 who would be expected to have mtDNA identical to that of the living relative, G.