Question 1: Define vaccination and explain how it helps to protect individuals and populations from infectious diseases.

Answer: Vaccination involves introducing a weakened, killed, or fragment of a pathogen into the body to stimulate the immune system to produce memory cells. This provides immunity by enabling the body to recognise and fight the pathogen more effectively in future infections.

Question 2: Describe the mechanism by which a vaccine stimulates immunity in the body.

Answer: A vaccine introduces antigens from a pathogen into the body, prompting the immune system to produce specific antibodies and memory cells. This prepares the immune system to respond swiftly and effectively if the actual pathogen enters the body in the future.

Question 1: A vaccine contains 0.5 ml of a solution with a concentration of 10^8 virus particles per millilitre. How many virus particles are in a single dose?

Answer: 5 x 10^7

Question 2: If a population of 10,000 people is vaccinated with a dose that provides immunity to 95% of recipients, how many people remain unprotected?

Answer: 500

Question 1: Design a simple experiment to test the effectiveness of a vaccine in a laboratory setting. Include the key variables and safety precautions you would use.

Answer: An experiment could involve dividing a suitable model organism or cell culture into two groups: one vaccinated and one unvaccinated. Expose both groups to the pathogen and monitor the infection rate. Variables include the type of vaccine, dose, and exposure time. Safety precautions include using protective equipment, sterilising equipment, and handling pathogens in a biosafety cabinet.

Question 1: In a study, 1000 individuals were vaccinated against a disease, and only 10 contracted the disease within a year. In a non-vaccinated group of 1000, 200 contracted the disease. Calculate the effectiveness of the vaccine and comment on its significance.

Answer: Vaccine effectiveness = ((200 - 10) / 200) x 100 = 95%. This indicates a high level of protection provided by the vaccine, significantly reducing disease incidence among vaccinated individuals.

Question 1: Explain why booster doses are often necessary after initial vaccination. (6 marks)

Answer: Booster doses are necessary to reinforce the immune response by stimulating memory cells, ensuring long-term immunity. Over time, antibody levels may decrease, and pathogens may mutate, so additional doses help maintain effective protection. Boosters also help respond to new strains and prevent disease resurgence.

Question 2: Which of the following is NOT a characteristic of an effective vaccine? A) Produces a strong immune response B) Contains live, unattenuated pathogens C) Is stable during storage D) Does not cause disease in recipients

Answer: B

Question 1: Describe how mRNA vaccines work and provide an example of a disease for which they are used.

Answer: mRNA vaccines deliver a piece of genetic material that encodes a pathogen's protein, prompting cells to produce the protein and stimulate an immune response. An example is the COVID-19 mRNA vaccines.