1.1. The diagram shows the human alimentary canal.

(i) Explain how food passes down the oesophagus.

(2)

(ii) Which labelled structure produces bile?

(1)

(iii) Describe the role of bile in digestion.

(3)

1.2. Lipase inhibitors are chemicals that bind to lipase enzymes.

To test the effect of a lipase inhibitor, equal masses of full fat milk are placed into two test tubes.

Lipase inhibitor is added to one test tube.

Lipase is added to both test tubes and the pH of each solution is measured every five minutes.

The results are shown in the table.

(i) Calculate the mean rate of pH change per minute of the solution without lipase inhibitor.

(2)

(ii) Explain the difference in the changes of pH of the solutions in the two test tubes during the 20-minute period.

(2)

(iii) Doctors use this method to investigate the use of lipase inhibitor as a treatment for obesity.

• Give three volunteers a tablet containing the lipase inhibitor

  • Give another three volunteers a tablet with no lipase inhibitor

  • Give all the volunteers 100 cm³ of olive oil to drink

  • Measure the lipid concentrations in the blood of the volunteers after three hours

Some of the volunteers reported abdominal pains three hours after drinking the olive oil.

The table shows the doctors’ results.

Discuss the use of the lipase inhibitor as a treatment for obesity.

Use the data from the table to support your answer.

(5)