Practise IB Biology HL 3.2.12 by relating HIV infection of helper T-cells to impaired B-cell activation, falling antibodies and AIDS progression.
Interactions in biological systems may have harmful or beneficial effects.
Discuss the consequences of infection with HIV.
a. HIV can be passed on/spread (by someone who is HIV positive);
b. HIV invades/infects/destroys helper T-lymphocytes / CD4 cells;
c. all (helper/CD4) T-lymphocytes gradually/eventually destroyed;
d. B-lymphocytes not (sufficiently) activated without T-lymphocytes;
e. antibodies not produced (in sufficient quantity);
f. immunity to new infections/pathogens cannot develop / antibodies not produced in response to new pathogens/antigens
g. opportunistic infections cannot be controlled/eliminated / valid example of an opportunistic infection;
h. AIDS/acquired immune deficiency syndrome (develops);
i. rapid mutation rate in HIV so evades immune system/resists (anti-retroviral) drugs;
Marking guidance:
Allow T-cells instead of T-
lymphocytes and B-cells
instead of B-lymphocytes.
Mark point a is awarded for spread of HIV from an infected person, not for spread to an uninfected person, because the question asks about the
consequences of infection.
Do not award mark point for
mark point g for understatements such as 'reduced immunity'.
4
max