pmt communicable diseases

Question 1

describe the actions of B lymphocytes in the immune response

Answer 1

-B-cell has an antigen receptor specific to only one antigen

-clonal selection: selection/ activation of specific B lymphocytes via macrophages/ antigen presenting cells/ T helper cells/ cytokinins/ interleukins

-clonal expansion: divides by mitosis/ clones

B cells differentiate to form plasma cells which secrete/ produce antibodies, antibodies are complimentary to antigen.
B cells form memory cells- long lived and produce a secondary response

Question 2

why can people sometimes lose immunity

Answer 2

-no repeat infections
-limited life for memory cells, so no secondary response

Question 3

suggest why the resistance of MRSA to existing antibiotics is a major concern to humans

Answer 3

-potential disease outbreak/ epidemic
-developing new antibiotics takes time
-MRSA is harder to treat/ may become untreatable

Question 4

how does fossil evidence show that evolution has occurred over time

Answer 4

-fossils show that organisms have changed over time
-fossils or rocks can be dated
-fossils show intermediate forms