Biology and Human Welfare
Biology and Human Welfare combines human health and disease, microbes in human welfare, and plant breeding. The exam asks for pathogen-disease pairs, immune responses, industrial microbes, breeding methods, and biofortification.
Core rules
- Pathogens: Plasmodium causes malaria, Wuchereria causes filariasis, Ascaris causes ascariasis, and HIV causes AIDS. Innate immunity is non-specific; acquired immunity has B cells for humoral responses and T cells for cell-mediated responses.
- AIDS: HIV infects helper T cells; diagnosis is by ELISA; treatment is antiretroviral therapy, not a vaccine.
- Cancer: uncontrolled cell division; benign tumours do not spread, malignant tumours metastasise.
- Microbes: Lactobacillus makes curd; Saccharomyces cerevisiae makes bread and alcohol; Aspergillus niger gives citric acid; Penicillium notatum gives penicillin; Trichoderma polysporum gives cyclosporin A; Monascus purpureus gives statins.
- Plant breeding: variation, selection, evaluation, and release. Semi-dwarf wheat and rice drove the Green Revolution. Biofortification breeds for micronutrients.
Worked example
Match cyclosporin A and statins with their microbial sources and uses. Reasoning: cyclosporin A is from Trichoderma polysporum and is an immunosuppressant used in organ transplantation. Statins are from Monascus purpureus and lower blood cholesterol by inhibiting HMG-CoA reductase.
Traps
Antibiotics are not antibodies. Penicillin is from Penicillium notatum, not from a bacterium. Rhizobium fixes nitrogen in legume root nodules; it is not a free-living soil fixer in the same way. Biofortification is breeding, not fortification of food after processing. Colostrum is rich in IgA.