CAIE A Level Biology 9700 · Immunity
Influenza viruses infect the epithelial cells of the respiratory tract. During a primary infection with a new influenza strain, the body mounts an immune response. Explain the roles of different types of white blood cells in this response, paying particular attention to the distinct roles of T-helper lymphocytes and T-killer lymphocytes.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.