1 a) Explain how the use of nitrate-rich fertilisers has led to the destruction of freshwater ecosystems.
b) What is the name given to this process?
c) Name two areas in Britain where this has occurred.
2 List all the factors which might limit the algae population in a fresh water system. Which one of your list is most likely to be the factor limiting the growth of the algae?
3 Why does the addition of nitrate to the soil result in improved plant growth and crop yield?
4 What is the role of nitrate reductase?
5 How did scientists turn off the nitrate reductase gene in the roots of their experimental plants?
6 How could switching on the gene for nitrate reductase throughout the life of a plant help us to deal with the problem of excess nitrate entering freshwater ecosystems?
7 Make a list of the organic nutrients needed for plant growth and development. Explain what each is used for.
