(a)[1]
State when DNA replication happens in the cell cycle.
(b(i))[1]
Name the bond type represented by the dotted lines between the bases.
(b(ii))[1]
State which base, X or Y, is a pyrimidine and explain your answer.
(c(i))[2]
State what is meant by the term gene mutation.
(c(ii))[2]
Mutations that occur in dividing cells of the gas exchange system may cause cancer. Suggest the differences in the cell cycle of a cancer cell compared with that of a normal cell of the same type.