22.3.3 Graphs, charts and statistics question 1
Fig. 4.1 is a diagram of a virus.

Fig. 4.1
The human immunodeficiency virus (HIV) infects and destroys lymphocytes.
The number of lymphocytes in the blood of a person infected with HIV was measured over a period of 84 months.
The results are shown in Fig. 4.2.
number of lymphocytes per of blood

Fig. 4.2
Describe the changes in the number of lymphocytes, over the 84 months following infection with HIV, shown in Fig. 4.2.