immune response

Question 1

what is an antigen?

Answer 1

proteins on the cell surface membrane that stimulate an immune response

Question 2

what do antigens allow the immune system to identify?

Answer 2

pathogens, cells from other organisms of the same species, abnormal cells, toxins

Question 3

what is a pathogen?

Answer 3

any micro organism that causes disease

Question 4

what is the biological importance of antigens?

Answer 4

pathogens, cells from other organisms of the same species, toxins and abnormal cells are all potentially harmful.
if the immune system can recognise or differentiate between self and non-self cells, then a quick response to destroy non-self cells reduces the risk of harm

Question 5

what are potential problems with antigens?

Answer 5

transplants may be rejected so immunosuppressant drugs have to be used, blood transfusions

Question 6

what is antigenic variability?

Answer 6

antigens can change due to genetic mutations

Question 7

why is antigenic variability a problem for the immune system?

Answer 7

surface receptors on lymphocytes and memory cells that produce antibodies are only complementary to one specific antigen. if the shape of the antigen changes, the antibody is no longer complimentary, meaning there is a reinfection

Question 8

what is a non-specific defence mechanism?

Answer 8

the response is immediate and the same for all pathogens, such as a physical barrier and phagocytosis

Question 9

what is a specific defence mechanism?

Answer 9

the response is slower but more long lasting and it is specific to each pathogen, such as cell mediated response and humoral response