On the 19th March 1899, Charles 'Cheers' Wakefield set up an oil company in England. Ten years later, he produced a new lubricant that would revolutionise transport in the first half of the twentieth century. He called the new oil Castrol. To this day this name is synonymous with premium quality, high performance and leading edge technology in lubrication. (see positioning map below).

11. Are membranes only present as the outside of cells?

12. Which type of cell evolved first, the eukaryotic cell or the prokaryotic cell?

13. Regarding the presence of the nucleus, what is the difference between animal and bacterial cells?

14. What are the three main parts of a eukaryotic cell?

15. What are the main structures within the nucleus of a cell?

16. What substances is chromatin made up of? What is the difference between chromatin and a chromosome?

17. What is the fluid that fills the nucleus called?

18. What substances make up the nucleolus? Is there a membrane around the nucleolus?

19. What is the name of the membrane that encloses the nucleus? Which component of cell structure is contiguous to this membrane?

20. What are the main structures of the cytoplasm present in animal cells?