gce winter 2010 - question paper - KCSE Online

4
Examiner
only
2. Fill in the gaps in the following passage.
The specific immune response is triggered by the introduction into the body of large foreign
molecules called ................................................................................ The body’s defence depends upon two
types of ............................................................................... referred to as B and T cells. The B cells are formed
in the ............................................................................... and multiply rapidly in response to infection,
forming plasma cells. These produce specific ...............................................................................molecules
which are secreted into the blood stream as antibodies. In addition to plasma cells, the B cells
form ..............................................................................
cells which remain in the bloodstream, ready to
proliferate if the same infection occurs in the future. The T cells mature in the
............................................................................... gland and retain their antibody on the cell surface. They
are responsible for what is known as ............................................................................... immunity. If a virus
infects body cells, the T cells carrying the antibody for that virus multiply rapidly to form a
............................................................................... . Some of these eliminate the virus by causing
............................................................................... of the infected cell and these T cells are called
............................................................................... cells. Other cells known as
............................................................................... cells, stimulate B cells to divide and form plasma cells.
(Total 11 Marks)
(314-01)