Control of blood glucose concentrationAQA A-Level Biology: Mind map

Exam questions on Control of blood glucose concentration

1. A healthy adult eats no food for 14 hours. During this time the concentration of glucose in her blood stays at about 4.5 mmol dm⁻³, even though no glucose is being absorbed from her gut. Her liver cells are responsible for much of this regulation.
   Glucagon is released when blood glucose concentration falls. State two ways in which glucagon increases the concentration of glucose in the blood.2 marks
2. A researcher adds insulin to cultured muscle cells. Within minutes, the uptake of glucose by the cells increases, and the number of glucose channel proteins in the cell surface membrane is found to be greater than before. The concentration of glucose in the surrounding solution is the same throughout.
   Insulin also activates enzymes inside the muscle cells. Explain how this helps to increase the uptake of glucose.2 marks
3. A clinic is testing the urine of two patients with diabetes: patient 1 has type I diabetes and patient 2 has type II diabetes. The clinic estimates glucose concentration using Benedict's reagent and a colorimeter with a red filter. Standard glucose solutions of 0.0, 0.2, 0.4, 0.6 and 0.8 mmol dm⁻³ gave absorbances of 0.90, 0.72, 0.54, 0.36 and 0.18, because less blue copper(II) remains as glucose concentration increases. A urine sample from patient 2 was diluted by mixing 1 cm³ of urine with 9 cm³ of distilled water, and the diluted sample gave an absorbance of 0.45.
   Explain why patient 1 needs insulin injections, but patient 2 may be able to control their blood glucose concentration by changing their diet.3 marks