Question 21M.2.SL.TZ1.4a
| Date | May 2021 | Marks available | [Maximum mark: 3] | Reference code | 21M.2.SL.TZ1.4a |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | a | Adapted from | N/A |
Plasma cells secrete antibodies against specific antigens. Outline how plasma cells become activated.
[3]
a. macrophages/phagocytes recognize/engulf pathogen and display antigens ✔
b. antigen binds to T cell/helper T cell / antigen causes activation of T cell ✔
c. antigen binds to antibodies in membrane of B cells ✔
d. (activated) T cells activate B cells (that have the antigen bound to them) ✔
e. activated B cells divide to produce a clone of cells ✔
f. active plasma cells develop from the clone of cells/from activated B cells ✔
Accept B-lymphocyte and Tlymphocyte instead of B cell and T cell throughout the answer.
Some explanations of the production of active plasma cells were excellent but weaker candidates were mostly very confused, with antigens and antibodies muddled up. Many candidates thought that plasma cells are already present and just need to be activated, rather than them being produced as a result of the activity of macrophages, T-cells and B-cells. There was too much focus on memory cells. The mean mark was low, 0.6 out of 3.
