1.1. Figure 1 below outlines the mechanism of lipid digestion and absorption.

Figure 1

Identify the type of cell labelled cell A.

1.2. Figure 1 shows the formation of lipid droplets and micelles.

Explain how the presence of these structures aids digestion and/or absorption.

1.3. Triglycerides are hydrolysed by the enzyme lipase.

A student wanted to investigate the breakdown of triglycerides in cow milk by human lipase at 20 °C. They recorded the pH of a sample of milk before and after adding human lipase. They used a pH meter to measure the pH.

Their results are shown in figure 2.

Figure 2

Explain the changes in pH after human lipase is added.

1.4. The student carried out the experiment at a controlled temperature of 20 °C. They repeated the experiment at 25 °C.

Draw a line on the graph (Figure 2) to show the results you would expect at 25 °C.