Diseases and immunity

6 Describe active immunity as defence against a pathogen by antibody production in the body

7 State that each pathogen has its own antigens, which have specific shapes

8 Describe antibodies as proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes

9 State that specific antibodies have complementary shapes which fit with specific antigens

10 Explain that active immunity is gained after an infection by a pathogen or by vaccination

11 Outline the process of vaccination: (a) weakened pathogens or their antigens are put into the body (b) the antigens stimulate an immune response by lymphocytes which produce antibodies (c) memory cells are produced that give long-term immunity

12 Explain the role of vaccination in controlling the spread of diseases

13 Explain that passive immunity is a short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk

14 Explain the importance of breast-feeding for the development of passive immunity in infants

15 State that memory cells are not produced in passive immunity

16 Describe cholera as a disease caused by a bacterium which is transmitted in contaminated water

17 Explain that the cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss of ions from the blood