6.3 Defence against infectious disease

1.What is a characteristic of antigens?

2. What can protect the body from blood loss?

3. Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is based on DNA sequences and the cladogram on the right is based on comparing protein sequences. What is the reason that cladograms based on DNA sequences are more reliable predictors of the phylogenetic relationship of species than cladograms based on protein sequences?

4. The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive system. The graph shows the percentage of samples in which this bacterium showed resistance to six antibiotics over a period of ten years. What is a possible explanation for the total percentage resistance being larger than 100% in 2010?

5. Why is penicillin not used in the treatment of human immunodeficiency virus (HIV)?

6. In Florey and Chain’s experiment, eight mice were infected with lethal doses of Streptococcus bacteria. The four mice given penicillin survived, but the untreated mice died. What can be concluded from these results?

7. Which statement is true for the antibiotic penicillin?

8. Which is the correct statement concerning HIV and AIDS?

9. Which is the correct statement concerning HIV and AIDS?

10. The graph is about defence against infectious disease. What is likely to be indicated by the letter X?

11. Why are antibiotics effective against pathogenic bacteria?

12. What steps occur in blood clotting?

13. Where are structures I, II and III found in the human body?

14. What are antibodies?

15. Formation of a blood clot by damaged tissue involves the series of steps outlined in the following diagram. Which letter represents a soluble globular protein that will be converted into an insoluble protein during clot formation?

16. What is a consequence of AIDS?

17. What effect does HIV have on the immune system?

18. Which reaction during blood clotting is catalysed by the enzyme thrombin?

19. What is a long-term effect of HIV on the immune system?

20. Which of the following statements about antibodies is correct?

21. Which of the following statements about antibodies is correct?

22. What are two effects of HIV on the immune system?

23. Why are antibiotics effective against bacteria?

24. What is an effect of the HIV virus on the immune system?

25. What prevents antibiotics from being effective against viruses?

26. What occurs during the blood clotting process?

27. What stimulates the production of antibodies?

28. Which term describes a molecule capable of triggering an immune response?

29. Why are antibiotics effective against bacteria but not viruses?