1. What are the three main types of biological factors that affect the health of a community? Explain how each one can influence the incidence and prevalence of diseases. (5 marks) Answer: The three main types of biological factors are pathogens, parasites and genetic variations. Pathogens are microorganisms that cause infectious diseases, such as bacteria, viruses, fungi and protozoa. They can spread through direct or indirect contact, vectors, contaminated food or water, or airborne transmission. Parasites are organisms that live on or in another organism and benefit at the expense of the host, such as worms, lice and mites. They can cause malnutrition, anemia, skin infections and allergic reactions. Genetic variations are differences in the DNA sequence among individuals of the same species, such as blood groups, sickle cell trait and cystic fibrosis. They can affect the susceptibility or resistance to certain diseases, the response to drugs or vaccines, or the expression of physical or behavioral traits. 2. How do genetic factors interact with environmental factors to affect the health of a community? Give two examples of gene-environment interactions and their health implications. (5 marks) Answer: Genetic factors interact with environmental factors to modify the risk or severity of diseases. For example, people with sickle cell trait have a lower risk of malaria infection because their red blood cells are less hospitable to the malaria parasite. However, if they live in areas with low oxygen levels, such as high altitudes or polluted cities, they may develop sickle cell crisis, which is a painful condition that blocks blood vessels and damages organs. Another example is people with lactose intolerance, who have a reduced ability to digest lactose, a sugar found in milk and dairy products. If they consume lactose-rich foods, they may experience abdominal pain, bloating, diarrhea and gas. However, if they live in areas where dairy products are scarce or expensive, they may have a higher risk of calcium deficiency and osteoporosis. 3. What are the four main types of physical factors that affect the health of a community? Explain how each one can influence the exposure and adaptation to environmental hazards. (5 marks)