Synthetic glucagon is frequently administered to patients experiencing severe hypoglycaemia. Which of the following pathways correctly describes the molecular cascade initiated by the binding of glucagon to its target cells in the liver?
Glucagon binds to a transmembrane receptor →\rightarrow→ activates adenylate cyclase →\rightarrow→ converts ATP to cAMP →\rightarrow→ activates protein kinase A →\rightarrow→ promotes glycogenolysis
Glucagon binds to a transmembrane receptor →\rightarrow→ activates adenylate cyclase →\rightarrow→ converts ADP to cAMP →\rightarrow→ inhibits protein kinase A →\rightarrow→ promotes glycogenesis
Glucagon diffuses across the phospholipid bilayer →\rightarrow→ binds to an intracellular receptor →\rightarrow→ acts as a transcription factor →\rightarrow→ upregulates glucose-6-phosphatase expression
Glucagon binds to a transmembrane receptor →\rightarrow→ activates tyrosine kinase →\rightarrow→ triggers vesicle fusion →\rightarrow→ increases translocation of GLUT4 glucose transporters
23 exam-style questions on OCR GCSE Biology 3.2 Coordination and control – the endocrine system, covering 3.2.1 Principles of hormonal coordination and control, 3.2.2 Roles of thyroxine and adrenaline, 3.2.3 Hormones in human reproduction, 3.2.4 Interactions of reproductive hormones, 3.2.5 Hormones in contraception, 3.2.6 Hormones in reproductive technologies, 3.2.7 Plant hormones in growth and coordination, 3.2.8 Effects of plant hormones, and 3.2.9 Uses of plant hormones. Each one has a worked solution and a mark scheme showing where the marks go.