3.6.7: Control of glucose concentration

Question 1

Describe the role of glucagon in
gluconeogenesis.

Answer 1

1. (Attaches to receptors on target cells and) activates/stimulates
   enzymes;
   Reject ‘produces enzymes’.
2. Glycerol/amino acids/fatty acids into glucose;
   Reject ‘glucagon converts’ as context suggests enzyme action.
   Reject occurs in pancreas.

Question 2

Explain how inhibiting adenylate cyclase may
help to lower the blood glucose concentration.

Answer 2

1. Less/no ATP is converted to cyclic AMP/cAMP;
2. Less/no kinase is activated;
3. Less/no glycogen is converted to glucose
   OR
   Less/no glycogenolysis;
   If no indication of less/no for any of the mark points award max 2 marks.

Question 3

Using your knowledge of the kidney, explain why
glucose is found in the urine of a person with
untreated diabetes.

Answer 3

1. High concentration of glucose in blood/filtrate;
   Accept tubule for filtrate.
2. Not all the glucose is (re)absorbed at the proximal convoluted tubule;
   Reject no glucose is (re)absorbed.
3. Carrier/co-transport proteins are working at maximum rate OR
   Carrier/co-transport proteins/ are saturated;

Question 4

Adrenaline binds to receptors in the plasma
membranes of liver cells. Explain how this
causes the blood glucose concentration to
increase.

Answer 4

1. Adenylate cyclase activated / cAMP produced / second messenger
   produced;
2. Activates enzyme(s) (in cell so) glycogenolysis / gluconeogenesis occurs
   / glycogenesis inhibited;

Question 5

Explain why a pancreas transplant would not be
a suitable treatment for type 2 diabetes.

Answer 5

1. Type II produces insulin
2. Cells/receptors are less sensitive/responsive (to insulin) OR Faulty insulin
   receptors;
3. (treated/controlled by) diet/exercise