Chemical Signalling

9.Which of the following statements about cytokines are correct? (select all that apply)

10.Which of the following are true of steroid hormones? (select all that apply)

11.Match each signalling molecule with its correct category.

12.Match each component of the epinephrine signal transduction pathway in a liver cell with its correct role.

13.Place the steps of the epinephrine signal transduction pathway in the correct order.

14.Arrange the steps of the oestradiol stimulation pathway in the correct sequence.

15.Positive feedback is used in the majority of homeostatic control mechanisms in organisms.

16.G-proteins are activated when GTP replaces GDP.

17.Adenylyl cyclase catalyses the conversion of cAMP to ATP.

18.In the bacterium Vibrio fischeri, bioluminescence is only produced when the colony is large enough. Which statement best explains why?

19.A student records the membrane potential of a postsynaptic neurone before and after glycine binds to its receptors. The potential becomes more negative. Which conclusion is best supported?

20.Scientists measured the percentage of successful ligand–receptor bindings at a ligand concentration of 3 μm. Ligand A gave 60 % and ligand B gave 15 %. What is the percentage difference between ligand A and ligand B?

21.A graph shows that for ligand A the percentage of successful bindings rises steeply up to about 2 μm and then stays almost constant at roughly 80 % as concentration increases further. Which conclusion is best supported?

22.Two groups of mice were fed either a normal diet or a high-fat diet for three weeks. After a meal, the high-fat group had a higher peak blood insulin concentration, but insulin levels in both groups had fallen to similar low values by 90 minutes. Which conclusion cannot be drawn from these data?

23.Which of the following statements about calcium ions in cell signalling are correct? (select all that apply)

24.AHR ligands bind to AHR receptors in endometrium cells and reduce the risk of endometrial cancer. Which statements about this anti-oestrogenic action are consistent with the information given? (select all that apply)

25.A ligand binds to the extracellular region of a transmembrane receptor, causing a change in shape of the internal region of the protein.

26.In quorum sensing, a change in gene expression in a bacterial colony is triggered when a threshold number of receptors are occupied by ligands.

27.Match each signalling molecule with the correct description of its role.

28.Place the steps of the oestradiol stimulation pathway in the correct order.

29.At a ligand concentration of 3 μm, ligand A gives 60 % successful binding and ligand B gives 15 %. Which statement about the trend is correct?

30.A student investigates ligand–receptor binding by measuring the percentage of successful bindings at increasing ligand concentrations. Which of the following is the most appropriate control for this experiment?

31.A scientist wants to determine whether a newly discovered signalling molecule works by binding to a transmembrane receptor or an intracellular receptor. Which of the following observations would support the conclusion that it binds to an intracellular receptor? (select all that apply)

32.In an experiment investigating cell signalling, increasing the ligand concentration always increases the percentage of successful bindings indefinitely.

33.Match each experimental observation with the correct conclusion about the signalling molecule.

34.Place the steps of the epinephrine signal transduction pathway in the correct order, starting with the binding of epinephrine.

35.At a ligand concentration of 3 μm, ligand A gives 60% successful binding and ligand B gives 15%. Which statement about the trend is correct?

36.The scientists hypothesised that increasing the concentration of ligands was a requirement for improving the successful binding to receptors. Which of the following statements explain why this hypothesis may be incorrect? (select all that apply)

37.In an experiment, cells are treated with a drug that prevents the dissociation of the G-protein subunits from the GPCR. What effect would this most likely have on the signal transduction pathway?

38.In the epinephrine signal transduction pathway, the enzyme cascade amplifies the signal so that one epinephrine molecule can lead to the breakdown of many glycogen molecules.

39.Which of the following best defines the term ligand?

40.Which of the following correctly defines a hormone?

41.Name the second messenger produced when adenylyl cyclase is activated by epinephrine binding to a liver cell receptor.

42.At a synapse, neurotransmitters diffuse across the synaptic cleft. If this distance is 20 nanometres, what is the distance in metres? Give your answer in scientific notation.

43.Complete the sentence about cell signalling.

44.What term describes a molecule that binds specifically to a receptor?

45.Complete the sentence about the action of insulin.

46.At a synapse, the average distance for neurotransmitters to diffuse across the synaptic cleft is 20 nanometres. Express this distance in metres using scientific notation.

47.Complete the sentences about the insulin signalling pathway.

48.At a cholinergic synapse, acetylcholine molecules must diffuse across the synaptic cleft, an average distance of 20 nanometres. Express this distance in metres using scientific notation. Give your answer as the coefficient only (e.g. if the answer is 2 × 10⁻⁸ m, enter 2).

49.At 3 μm, ligand A gives 60 % and ligand B gives 15 %. Calculate the percentage difference between ligand A and ligand B. Give your answer as a percentage.

50.Name the intracellular receptor protein that oestradiol binds to within the nucleus of a target cell.

51.Complete the sentence about the epinephrine second messenger pathway.

52.Neurotransmitters diffuse across the synaptic cleft, an average distance of 20 nanometres. Express this distance in metres using scientific notation.

53.Compare and contrast neurotransmitters and hormones as chemical signalling molecules.

54.Explain how the binding of a steroid hormone such as oestradiol to its intracellular receptor can lead to a change in gene expression.

55.Suggest how the activation of glycine receptors may affect the postsynaptic membrane potential.

56.Scientists hypothesised that increasing the concentration of ligands was a requirement for improving the successful binding to receptors. Explain why this hypothesis may be incorrect. Use all the information presented in the question.

57.Activation of AHR ligands can lead to anti-oestrogenic actions. Suggest the role of AHR ligand molecules in activating an anti-oestrogenic action in endometrium cells.

58.At a synapse, neurotransmitters diffuse across the synaptic cleft. If this distance is 20 nanometres, what is the distance in metres? Give your answer in scientific notation.

59.At a synapse, the average distance for neurotransmitters to diffuse across the synaptic cleft is 20 nanometres. Express this distance in metres using scientific notation.

60.At a cholinergic synapse, acetylcholine molecules must diffuse across the synaptic cleft, an average distance of 20 nanometres. Express this distance in metres using scientific notation. Give your answer as the coefficient only (e.g. if the answer is 2 × 10⁻⁸ m, enter 2).

61.At 3 μm, ligand A gives 60 % and ligand B gives 15 %. Calculate the percentage difference between ligand A and ligand B. Give your answer as a percentage.

62.Neurotransmitters diffuse across the synaptic cleft, an average distance of 20 nanometres. Express this distance in metres using scientific notation.