1.1. Monoglycerides are molecules made up of glycerol and one fatty acid tail. They are absorbed into the epithelial cells of the small intestine by diffusion across the cell membrane.

A scientist measured the uptake of monoglycerides in the epithelial cells of mice. In the investigation, the scientist provided the mice with different concentrations of monoglycerides and measured the uptake into the epithelial cells of the small intestine.

Complete Table 1 to show which variables the scientist used in this investigation.

Table 1

1.2. The graph in Figure 3 shows the results of the investigation from part (a).

Figure 3

Describe and explain what the graph shows.

1.3. Human body temperature is approximately 37 °C, which provides the optimum temperature for activity of protein molecules such as enzymes.

Suggest why a temperature of 37 °C helps to maximise the rate of transport of substances across the cell membrane.

1.4. Figure 4 shows the concentration of sugars in three different cells. X, Y and Z.

Figure 4

Which of the following statements is correct?