Below are Michelin star ratings for the difficulties of the problems:

1. * Easy, even though might be long

2. ** Average, you should be able to cope

3. *** Hard, not obvious what to do, but not necessarily long

These ratings are based on my own opinions and on the experiences of students who have had to do battle with many of the problems. It's fairly certain that you will not find all the ‘Easy’ questions to be easy, but starting with them is still a good idea.

Comments after the ratings are intended as helpful hints

1. Problem 1 ** Note carefully the volumes of sulphuric acid and chloroform that are used.

2. Problem 2 * (some parts) ** (some parts) Read about logarithms.

3. Problem 3 **

4. Problem 4 * The x's cancel out.

5. Problem 5 *(*) Not quite so easy.

6. Problem 6 ** Just bash through – no great difficulties.

7. Problem 7 ** Read about enzymes and energy metabolism.

8. Problem 8 * It's tedious though.

9. Problem 9 *** The maths may be hard for some people. Read about logarithms.

10. Problem 10 *

11. Problem 11 * Divide % (w / w) by atomic weights.

12. Problem 12 *

13. Problem 13 **

14. Problem 14 **

15. Problem 15 *(*) Few get this right. Pick up clues in the introductory material.

16. Problem 16 *

17. Problem 17 *** No student can do this. It is essentially the glutamate synthase calculation (see Chapter 8: Enzymes) in reverse.

18. Problem 18 * Keep track of volumes: ml of what at all stages.

19. Problem 19 **(*)

20. Problem 20 **

21. Problem 21 *(*) Easy if you can do restriction mapping.

22. Problem 22 ** Long, but not hard if you follow the sequence of steps.

23. […]