(a(i))[2]
Explain why the DNA sample is heated to $95\,^{\circ}\mathrm{C}$ in step 1.
(a(ii))[2]
Explain why primers are introduced in step 2.
(a(iii))[2]
Explain why the enzyme $\textit{Taq}$ polymerase is used during step 3.
(b(i))[2]
Explain why a cell usually has more than $100$ copies of mtDNA, but only two copies of nuclear DNA.
(b(ii))[1]
All mitochondria in a zygote are inherited from the egg, not the sperm. Write the letters of the people in the family tree in Fig. 3.2 who would be expected to possess mtDNA identical to that of the living relative, G.