Human Health & Disease: Mistakes to Avoid

Culex vs Anopheles confusion: The most common NEET error. Anopheles = malaria; Culex = filariasis. Never swap them. Aedes = dengue (bonus context, not directly in NCERT chapter but appears in distractors).
IgA vs IgG — placenta vs colostrum: IgG crosses the placenta (transplacental passive immunity); IgA is in colostrum (secretory immunity). Many students incorrectly choose IgG for colostrum.
HIV destroys B-cells: Wrong. HIV specifically infects CD4+ T-helper cells. B-cells are not the target. The immune deficiency in AIDS is primarily of T-cell origin.
Active immunity = immediate: Wrong. Active immunity is slow to develop (days to weeks) because the body needs time to mount a primary immune response. Passive immunity is immediate.
Passive immunity has memory cells: Wrong. No memory cells are formed in passive immunity since the body did not produce the antibodies itself.
Benign tumour = cancer: Wrong. Only malignant tumours are cancers (they invade and metastasise). Benign tumours are not cancerous by definition.
Heroin vs morphine: Heroin (diacetylmorphine) is chemically derived from morphine; both come from Papaver somniferum. Students sometimes state that heroin IS morphine — they are distinct molecules.
Cocaine is a depressant: Wrong. Cocaine is a CNS stimulant (blocks dopamine reuptake). Heroin and alcohol are CNS depressants.
Innate immunity has memory: Wrong. Innate immunity has no memory. Memory cells are a hallmark of adaptive immunity.
ELISA is confirmatory for HIV: ELISA is the screening test; Western blot is the confirmatory test.