Name Class Date
1. (a) James Watson and Francis Crick built a model that showed that DNA has a double helix structure.
(i) Which statement about DNA is correct? (1 Mark)
A each pair of bases is joined by hydrogen bonds
B phosphate groups are joined by hydrogen bonds
C nucleotides consist of a sugar and a phosphate group only
D bases are joined to phosphate molecules
(b) The below graph shows the percentage of each base in human DNA.
Describe how this data provides evidence for base pairing in DNA. (2 Marks)
(c) A student used the method shown below to compare the mass of DNA extracted from
strawberry fruit cells and from kiwi fruit cells.