Practice IB Biology Topic C2.1 Chemical Signalling with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for C2.1 Chemical Signalling and mirrors Paper 1A, 1B, 2 style where relevant.
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Refer to the diagram showing epinephrine binding to a beta-adrenergic receptor and subsequent activation of intracellular signalling.
Epinephrine-stimulated cAMP synthesis
Which process best explains the first intracellular event in signal transduction immediately after epinephrine binds to the receptor?
A researcher measured the effect of a ligand binding to a GPCR on cAMP production in liver cells. The data is shown below:
The graph shows the response of cells to a ligand alone, and to the same ligand together with drug X. What is the most likely action of drug X?
Figure: Response to a ligand with and without drug X
…
| Ligand Concentration (nM) | cAMP Production (pmol min) |
|---|
| 0 | 1.0 |
| 5 | 3.8 |
| 10 | 7.5 |
| 25 | 15.2 |
| 50 | 18.5 |
| 100 | 19.0 |
(a) the relationship between ligand concentration and cAMP production using the data provided.
(b) why cAMP production reaches a maximum level when ligand concentration exceeds 50 nM.
Epinephrine (adrenaline) prepares the body for action by triggering rapid responses in target cells such as liver cells.
(a) how a G protein-coupled receptor conveys a signal to the interior of the cell.
(b) the role of cyclic AMP (cAMP) as a second messenger in a liver cell's response to epinephrine.
(c) how the epinephrine signalling pathway amplifies the original signal.
(a) between the mechanisms by which the epinephrine receptor and the insulin receptor relay their signals into a target cell.
(b) how the actions of epinephrine and insulin on liver cells have opposite effects on blood glucose concentration.
(c) how the strength and duration of a target cell's response to a hydrophilic hormone are controlled.
A G-protein subunit activates adenylyl cyclase by direct interaction at the membrane.
The receptor’s cytoplasmic domain causes dissociation of G-protein subunits.
The activated G-protein directly hydrolyzes ATP into cyclic AMP and phosphate.
The ligand–receptor complex enters the nucleus to initiate transcription directly.
