Question 1: Define the term 'antigen' and explain its role in the immune response.

Answer: An antigen is a substance that triggers an immune response, usually a protein on the surface of pathogens, allowing the immune system to recognise and attack the pathogen.

Question 2: Describe the mechanism by which phagocytes identify and destroy pathogens.

Answer: Phagocytes recognise pathogens through surface antigens, engulf them by phagocytosis, and then digest them with enzymes to destroy the pathogens.

Question 3: What is the primary function of memory cells in the immune response?

Answer: Memory cells provide long-term immunity by recognising a pathogen quickly if it invades again, leading to a faster and stronger immune response.

Question 1: If a vaccine dose contains 0.5 millilitres of antigen solution and a patient receives 3 doses, what is the total volume of antigen administered? (Answer in millilitres)

Answer: 1.5 ml

Question 2: A study shows that 85% of vaccinated individuals develop immunity within 7 days. If 200 people are vaccinated, how many are expected to develop immunity?

Answer: 170

Question 1: Design a simple experiment to test the effect of handwashing on the presence of bacteria. Include the variables involved and safety precautions.

Answer: Students could swab their hands before and after washing with soap, then culture the swabs on agar plates to compare bacterial growth. The independent variable is handwashing; the dependent variable is bacterial colonies. Variables to control include the type of soap and duration of washing. Safety precautions include wearing gloves, sterilising equipment, and disposing of cultures properly.

Question 1: A group of 50 vaccinated individuals was exposed to a pathogen. Data showed that 48 individuals developed symptoms within 2 days, while 2 remained asymptomatic. Explain what this data suggests about the effectiveness of the vaccine.

Answer: The data suggests that the vaccine is highly effective, as the vast majority of individuals developed immunity or were protected, with only 2 showing symptoms early, possibly due to individual variation or incomplete immunity.

Question 2: In a different scenario, a vaccinated population shows a 60% reduction in infection rates compared to unvaccinated groups. What factors could contribute to this partial effectiveness?

Answer: Factors may include variations in individual immune response, vaccine storage and handling issues, pathogen mutation, or incomplete coverage of the population.

Question 1: Explain the role of vaccines in human defence systems. Include how they stimulate immunity and the importance of herd immunity.

Answer: Vaccines introduce weakened or inactive forms of pathogens or their antigens to stimulate the immune system without causing disease. This triggers the production of memory cells, providing long-term immunity. Vaccination helps protect individuals and contributes to herd immunity, reducing the spread of infectious diseases within a population.

Question 1: Describe how the development of mRNA vaccines represents an advancement in human defence against viruses.

Answer: mRNA vaccines use messenger RNA to instruct cells to produce viral proteins, which then stimulate an immune response. This technology allows rapid development, adaptability to virus mutations, and has proven effective in combating diseases like COVID-19.

Question 2: Discuss the potential benefits and challenges of developing universal vaccines against multiple strains of pathogens.

Answer: Universal vaccines could provide broad protection against multiple strains, reducing the need for frequent updates and increasing herd immunity. Challenges include identifying conserved antigens, ensuring effectiveness across strains, and addressing potential safety concerns. Research is ongoing to overcome these hurdles.