The interpupillary distance (IPD) is the distance in millimetres between the centres of the pupils of the eyes. Fig. 2.1 shows how IPD is measured. [Figure 2.1] IPD is one example of a characteristic of human facial structure that shows variation. Fig. 2.2 shows the pattern of variation in IPD in a large sample of adults. [Figure 2.2]

Fig. 7.1 shows two chromosomes in one stage of meiosis. The letters G to M represent the dominant alleles of seven ge...

The red blood cells of people with sickle cell anaemia have reduced oxygen-carrying capacity.

(a) Meiosis is an important process that contributes to genetic variation in a population. Fig. 4.1 shows a pair of h...

To prevent a disease, dead bacteria may be injected into the body. What type of immune response is produced?

The graph shows the amount of antibody produced in response to an antigen. [Figure 35.1] From the graph, which statem...

Which of the following two diseases are caused by viruses?