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

Answer: An antibody is a protein produced by plasma cells that specifically binds to antigens on pathogens, helping to neutralize or destroy them.

Question 2: Describe how the body's immune system recognizes a pathogen as foreign.

Answer: The immune system recognizes a pathogen as foreign through antigens present on its surface, which are detected by immune cells such as macrophages and lymphocytes.

Question 1: If a person produces 200,000 antibodies per second, how many antibodies are produced in 10 minutes? (Show your calculation.)

Answer: In 10 minutes (which is 600 seconds), total antibodies = 200,000 antibodies/second × 600 seconds = 120,000,000 antibodies.

Question 2: The rate of antibody production is proportional to the number of plasma cells. If each plasma cell produces 1,500 antibodies per hour, how many plasma cells are needed to produce 3,000,000 antibodies in 2 hours?

Answer: Number of plasma cells = Total antibodies / (antibodies per plasma cell × hours) = 3,000,000 / (1,500 × 2) = 3,000,000 / 3,000 = 1,000 plasma cells.

Question 1: Describe a safe method to test the effectiveness of a vaccine in a laboratory setting, considering variables and safety precautions.

Answer: A safe method involves using a controlled experiment with vaccinated and unvaccinated samples, ensuring proper sterilization and protective equipment. Variables include vaccine dose and exposure time. Safety precautions include wearing gloves, lab coats, and eye protection, and disposing of biological waste properly.

Question 1: A study shows that after vaccination, the average number of pathogens neutralized by antibodies increases from 100 to 950 per day. Explain what this data suggests about the immune response post-vaccination.

Answer: The data suggests that vaccination significantly boosts the immune system's ability to produce antibodies that neutralize pathogens, increasing from 100 to 950 pathogens per day, indicating an enhanced immune response.

Question 1: Explain the process by which white blood cells identify and destroy pathogens. Include key cell types involved. (6 marks)

Answer: White blood cells, such as macrophages, first detect pathogens via surface antigens. Macrophages engulf and digest the pathogens, presenting antigens to helper T cells. Helper T cells activate B cells to produce specific antibodies. Cytotoxic T cells then destroy infected cells. This coordinated response ensures efficient pathogen elimination.

Question 1: How has understanding of human immune responses contributed to the development of vaccines for diseases such as COVID-19?

Answer: Understanding immune responses has enabled scientists to design vaccines that stimulate the production of specific antibodies and memory cells, providing long-term immunity against diseases like COVID-19.