T-lymphocytes are formed in bone marrow and become mature in the thymus gland. After maturation, T-lymphocytes exit the thymus gland and move around the body. They stay inactive in organs such as the spleen and lymph nodes until antigens are present to activate them. Fig. 5.1 illustrates what occurs to two inactive T-lymphocytes, U1 and V1, when they encounter an antigen from a virus.
(a(i))[1]
U4 and V4 are kinds of active T-lymphocyte. State the names used for these types of T-lymphocyte.
U4
V4
(a(ii))[4]
Describe what cells U4 and V4 do in a primary immune response.
(b)[4]
Discuss the actions that health authorities must take during a vaccination programme if an infectious disease, such as polio, is to be eradicated worldwide.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “U4 is a T-helper cell and V4 is a T-killer cell” …