An investigation was carried out to determine the response of pancreatic cells to an increase in the glucose concentration of the blood. A person who had been told not to eat or drink anything other than water for 12 hours then took a drink of a glucose solution. Blood samples were taken from the person at one hour intervals for five hours, and the concentrations of glucose, insulin and glucagon in the blood were determined. The results are shown in the graph below.

a. i. Explain why the person was told not to eat or drink anything other than water for 12 hours before having the glucose drink.

ii. Use the information in the figure to describe the response of the pancreatic cells to an increase in the glucose concentration.

iii. Outline the role of insulin when the glucose concentration in the blood increases.

b. i. Suggest how the results will change if the investigation continued longer than five hours without the person taking any food.

ii. Outline the sequence of events that follows the binding of glucagon to its membrane receptor on a liver cell.

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10 1 300 insulin 8 - 240 F180 blood glucose 120 2 * 60 glucagon -60 60 120 180 240 300 Time/min glucose solution taken E Hormone concertration/pmol dm 6. 4. Blood glucose concertration/mmoldm-3