Fig. 1 shows the antibody concentration in the blood of a student who received two injections containing antigens from the same disease-causing bacterium. T...
Question 1 Report
Fig. 1 shows the antibody concentration in the blood of a student who received two injections containing antigens from the same disease-causing bacterium. The student did not have the disease before the first injection.
(a) Complete the statements about the first injection.
The antigens cause lymphocytes to make __________. These substances are carried around the body in the __________. [2]
(b) Describe the change in antibody concentration after the first injection, shown in Fig. 1. [3]
(c) Explain why the second injection gives the student better immunity to this disease. [4]
(d) Use Fig. 1 to state the approximate day on which the second injection was given. [1]
Answer Details
(a) Antigens cause lymphocytes to make antibodies. Antibodies are carried around the body in the blood. [2]
(b) After the first injection, antibody concentration remains low initially, then rises to a small peak, and falls again before the second injection. [3]
(c) The first injection produces memory lymphocytes, which remain in the body. On a second exposure to the same antigen, these cells divide rapidly and make antibodies rapidly. More antibodies are produced, giving a higher concentration and faster protection. [4]
(d) The second injection was given at approximately day 38. [1]
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