11 mark
Which of the following signalling molecules functions as a neurotransmitter?
Calcium ions
Cytokines
Amines
Steroids
Did this page help you?
Syllabus Edition
First teaching 2023
First exams 2025
|
Chemical Signalling (HL IB Biology)
Exam Questions
34 mins10 questions2
1 mark
1 markFigure 1 shows the cascade of events that occurs in a cell triggered by the binding of adrenaline to a receptor in the cell surface membrane.
Figure 1
Which is the second messenger shown in this response?
ATP
cAMP
Adrenaline
Adenyl cyclase
Did this page help you?
31 mark
1 markWhich of the following gives an example of positive feedback?
Thermoregulation
Regulation of blood glucose
Osmoregulation
Cervix dilation during childbirth
Did this page help you?
11 mark
1 markWhich of the following correctly describes the order of events after acetylcholine successfully binds to a receptor on the postsynaptic membrane?
Calcium ion channels open and calcium moves across the postsynaptic membrane triggering an action potential.
Positively charged ions diffuse through ion channels across the membrane causing a change in voltage across the plasma membrane.
An action potential is triggered when a threshold level of acetylcholine receptors are occupied.
Sodium ions are actively pumped across the membrane to initiate an action potential in the postsynaptic neurone.
Did this page help you?
21 mark
1 markWhich features are characteristic of transmembrane receptor proteins?
| External ligand binding site | Hydrophilic amino acids | Hydrophobic phospholipid tails | Non-polar | Intracellular domains | |
| A | ✓ | ✓ | ✓ | ✗ | ✓ |
| B | ✗ | ✓ | ✓ | ✗ | ✗ |
| C | ✓ | ✗ | ✗ | ✓ | ✓ |
| D | ✓ | ✓ | ✗ | ✗ | ✓ |
Did this page help you?
31 mark
1 markWhich of the following statements correctly describes the mechanism of action and effects of the steroid hormones oestradiol and progesterone on their respective target cells?
Oestradiol binds to receptors in hypothalamic cells, activating gonadotropin-releasing hormone (GnRH) secretion, by preventing the receptor from binding to specific DNA sequences and halting transcription of inhibitory genes.
Progesterone binds to intracellular receptors in endometrial cells, promoting gene transcription that supports endometrial thickening by binding to specific DNA sequences.
Oestradiol binds to receptors in endometrial cells, activating gene transcription to promote thickening of the uterine lining.
Progesterone binds to receptors in hypothalamic cells, promoting the release of GnRH by directly activating receptors on the plasma membrane.
Did this page help you?
41 mark
1 markA group of scientists wanted to investigate insulin production in mice. They fed one group of mice with a normal diet and another group with a ‘high fat’ diet (containing a high level of both fat and sugar) for three weeks beforehand. They then measured their blood insulin levels after a meal. Their results are shown in Figure 2 below.
Figure 2. Graph to show insulin production over time in two different groups of mice.
Which of the following conclusions cannot be drawn from the data given?
Consuming a 'high-fat' diet leads to a significantly higher peak in blood insulin levels in mice.
Insulin production is faster for the normal diet group in the first 10 minutes after consuming a meal.
Insulin production drops more rapidly for the normal diet group between 30 and 90 minutes after a meal.
Between 30 and 90 minutes after a meal, there was approximately a 90% decrease in insulin levels in the blood for mice on a 'high-fat' diet.
Did this page help you?