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O-Level Infectious Diseases in Humans
What the O-Level syllabus expects for Infectious Diseases in Humans, and how to practise it.
What the syllabus expects
- Note that infectious diseases can pass from one person to another while non-infectious ones cannot, and give examples of each kind.
- Account for infectious diseases being caused by pathogens like bacteria and viruses, which can move between people through body fluids, food and water.
- Note that a typical virus consists of a protein coat wrapped around its genetic material and can only reproduce inside living host cells.
- Note that a typical bacterial cell has a cell wall and DNA but no nucleus, and that some bacteria cause disease while others do not.
- Give what a person shows and feels when ill with influenza, which the influenza virus brings on, and with pneumococcal disease, which the bacterium pneumococcus brings on.
- Set out how the influenza virus and pneumococcus are transmitted and the ways that transmission can be cut down.
- Note that vaccines hold an agent resembling a pathogen and guard against infectious disease by prompting white blood cells to make antibodies rapidly when the pathogen enters.
- Account for how antibiotics act on bacteria by blocking the building of cellular structures, yet do not work on viruses because of differences in their structure and reproduction.
- Talk through how misusing and overusing antibiotics can speed up the rise of antibiotic-resistant bacteria.
Worked examples
Example 1 (2 marks)
Propose two approaches that could lower the number of young people infected with HIV in these countries.
Show the worked answer
HIV is spread mainly through unprotected sexual contact, so ways to lower infection in young people target transmission and awareness. Two approaches: (1) Education programmes about how HIV is transmitted and prevented, encouraging safer behaviour such as fewer sexual partners; (2) Promoting and providing free condoms, which act as a barrier and prevent transmission during sexual intercourse. Other acceptable answers: providing testing so infected people know their status and get treatment (antiretroviral drugs reduce transmission), or discouraging sharing of needles.
More O-Level Pure Biology topics
Cell Structure and Organisation · Movement of Substances · Biological Molecules · Nutrition in Humans · Transport in Humans · Respiration in Humans · all of O-Level Pure Biology