2023 AQA A-LEVEL BIOLOGY 7402/3 PAPER 3 QUESTION PAPER & MARK SCHEME (MERGED) JUNE 2023[VERIFIED]100% PASS

2023 AQA A-LEVEL
BIOLOGY 7402/3 PAPER 3
QUESTION PAPER &
MARK SCHEME
(MERGED) JUNE
2023[VERIFIED]100% PASS

,where are t-cells made?✔✔✔ANSWER➖thymus gland


where do b-cells mature?✔✔✔ANSWER➖bone marrow


what do b-cells do?✔✔✔ANSWER➖- humoral response
- release antibodies
- complementary to a specific antigen


what response are plasma
cells?✔✔✔ANSWER➖primary


what response are memory b-
cells?✔✔✔ANSWER➖secondary

,outline the humoral response✔✔✔ANSWER➖1. antigen
attaches to complementary antibody on b-cell
2. antigen taken into cell (endocytosis)
3. presented on cell surface membrane
4. t-helper cells bind to antigen and stimulate b-cell to
divide


what does mitosis do in humoral
response?✔✔✔ANSWER➖- forms clones of b-cells
(plasma and memory)
- clonal response


what do clones do?✔✔✔ANSWER➖each clone can
produce one type of antibody (monoclonal) which can be
used in medicine


outline plasma cells✔✔✔ANSWER➖- primary response
- secrete antibodies

, - only survive for a few day
- slow response = person gets ill before pathogen is killed


outline memory cells✔✔✔ANSWER➖- secondary
response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill


what is an antibody?✔✔✔ANSWER➖y-shaped globular
protein produced by b-cells


where are antibodies produced?✔✔✔ANSWER➖plasma
b-cells


what are antibodies made of?✔✔✔ANSWER➖4
polypeptide chains -- 2 heavy, 2 light