IB Biology HL · 2025
3.4 Chemical signalling
11 past paper questions from 9 papers across 4 exam sessions. See what repeats, then practise the same skills with AI marking.
Original Exam Vault questions with AI markscheme feedback for this topic.
HL archive · 2025 to 2026
3.4 Chemical signalling
Latest exam session: May 2026
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Micro-topics in 3.4 Chemical signalling
In syllabus order. The ring is the share of papers each appears in. 8 of them have no matching questions in this archive.
3.4.1
Receptors as proteins with binding sites for specific signalling chemicals
2 questions · in 11% of papers
Occasionallast Nov 25 P2 TZ3
- Regular
last May 26 P2 TZ3
3.4.3
2 questions · in 11% of papers
Occasionallast May 26 P2 TZ3
3.4.4
Chemical diversity of hormones and neurotransmitters
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it3.4.5
Localized and distant effects of signalling molecules
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it3.4.6
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it3.4.7
Initiation of signal transduction pathways by receptors
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it3.4.8
Transmembrane receptors for neurotransmitters and changes to membrane potential
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it3.4.9
Transmembrane receptors that activate G proteins
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it- Occasional
last May 26 P1 TZ3
- Less common
last Spec 25 P1
- Less common
last May 26 P1 TZ1
3.4.13
Effects of the hormones oestradiol and progesterone on target cells
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it3.4.14
Regulation of cell signalling pathways by positive and negative feedback
No question tagged to this topic in the 18 Biology HL papers analysed
No matches in this archiveRevise it
Exam pattern
How often each micro-topic has been examined, year by year. Each label is explained under the grid.
Does it repeat?
Top 4 of 6 micro-topics for the next sitting. Numbers are questions per year.
fewermore
| Micro-topic | 2025 | 2026 |
|---|---|---|
| 2Cell signalling by bacteria in quorum sensing, 2025: 2 questions | 1Cell signalling by bacteria in quorum sensing, 2026: 1 question | |
| ·Hormones, neurotransmitters, cytokines and calcium ions as examples of functional categories of signalling chemicals in animals, 2025: 0 questions | 2Hormones, neurotransmitters, cytokines and calcium ions as examples of functional categories of signalling chemicals in animals, 2026: 2 questions | |
| 1Mechanism of action of epinephrine (adrenaline) receptors, 2025: 1 question | 1Mechanism of action of epinephrine (adrenaline) receptors, 2026: 1 question | |
| 2Receptors as proteins with binding sites for specific signalling chemicals, 2025: 2 questions | ·Receptors as proteins with binding sites for specific signalling chemicals, 2026: 0 questions |
2 more micro-topics with a free account
- Regularin roughly one paper in six or more
- Occasionalin about one paper in ten
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Questions on 3.4 Chemical signalling, by exam session
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Frequently asked questions
Short answers about this page.
Which Biology HL exam sessions are covered for 3.4 Chemical signalling?
4 exam sessions from 2025 to 2026, the latest May 2026. Every Paper 1 and 2 in every timezone is read and classified in full, which gives 9 papers in this archive.
Which 3.4 Chemical signalling topic comes up most?
Cell signalling by bacteria in quorum sensing (3.4.2): in 17% of papers, last seen May 26 P2 TZ3. Usually "Identify", worth about 2 marks in a paper that includes it.
Can I see the original question and mark scheme?
No. The wording belongs to the IB. You get the citation, the marks, the command term and the skill tested, plus our own matched practice questions with worked answers and AI marking.
What do "banker", "due" and "rising" mean?
Banker: examined in at least one sitting in four and still appearing. Due: regular before, but absent for the last two exam sessions. Rising: clearly more common in the last two years. Our classification of real papers, not an IB statistic.
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