(a)[5]
Suggest and explain what effect this untreated sewage had on the lake ecosystem.
(b)[2]
Calculate the percentage increase in water transparency from 1957 to 1968.
(c(i))[4]
Use the data in Table 4.1 to describe how the distribution pattern of armour plates has altered over time.
(c(ii))[5]
Armour plates on the skin of a Three Spined Stickleback protect it from predators. Describe how natural selection may have led to the change in plate distribution over time.