Question 1: Define HIV and explain how it affects the immune system.

Answer: HIV is a virus that attacks the body's immune system, specifically targeting helper T cells, which reduces the body's ability to fight infections and diseases.

Question 2: Describe the process by which HIV is transmitted between individuals.

Answer: HIV is transmitted through exchange of body fluids such as blood, semen, vaginal fluids, and breast milk, typically via unprotected sexual contact, sharing needles, or from mother to child during childbirth or breastfeeding.

Question 3: What is AIDS and how does it relate to HIV infection?

Answer: AIDS is the advanced stage of HIV infection where the immune system is severely weakened, leading to increased vulnerability to opportunistic infections and certain cancers.

Question 1: If a population of 10,000 people has an HIV prevalence rate of 2%, how many individuals are estimated to be living with HIV in this population? (Show your working.)

Answer: 200. Calculation: 10,000 x 0.02 = 200

Question 2: The annual new HIV infection rate in a country is 0.5%. If the total population is 50 million, estimate the number of new infections per year. (Show your working.)

Answer: 250,000. Calculation: 50,000,000 x 0.005 = 250,000

Question 1: Describe a simple laboratory procedure to test a blood sample for HIV antibodies. Include safety precautions that should be taken.

Answer: A common test is the ELISA, where a small blood sample is mixed with specific HIV antigens. If HIV antibodies are present, they bind to the antigens. A secondary antibody with an enzyme is added, which produces a colour change if bound. Safety precautions include wearing gloves, using sterile equipment, and disposing of biohazardous waste properly.

Question 1: In a survey of 5,000 people, 150 tested positive for HIV. Calculate the prevalence rate and compare it to a country with a prevalence rate of 3%. Which population has a higher rate?

Answer: Prevalence rate = (150 / 5,000) x 100 = 3%. Both populations have the same prevalence rate of 3%, so they are equal.

Question 2: A study reports that in a community, the number of new HIV infections decreased from 300 to 180 over a year. What percentage decrease is this?

Answer: 40%. Calculation: ((300 - 180) / 300) x 100 = 40%

Question 1: Explain why HIV can be transmitted through unprotected sexual contact but not through casual contact such as hugging or sharing utensils. (6 marks)

Answer: HIV is transmitted through bodily fluids like semen and blood, which contain the virus, and require entry into the bloodstream. Casual contact such as hugging or sharing utensils does not involve exchange of these fluids, and the virus cannot survive or be transmitted through such means.

Question 1: Discuss how antiretroviral therapy (ART) helps manage HIV infection and reduces the risk of transmission.

Answer: ART uses a combination of drugs to inhibit the replication of HIV, reducing viral load in the body. This helps maintain immune function and decreases the chance of transmitting the virus to others.