IB Biology C2.1: Chemical signalling HL only (first exams in 2025)

This lesson can be purchased as part of the IB Complete course bundle (first exams 2025) at a heavily discounted price, formed of 40 fully resourced lessons, end of topic exams and student checklists. It can be found here

This PowerPoint contains everything you need to teach the Theme/Unit C2.1 Chemical signalling in the new IB Biology specification.

**YouTube video is a preview of the full resource (does not include all slides)
**
This Powerpoint consists of over 70 slides and contains the followings:

All the information the IB have included in the new spec.

Exam tips
Clear diagrams
Summary videos
Student research tasks
Clearly identified HL and SL content
Student checklist
Summary

The following content is included:

C2.1.1: Define the term ligand.
C2.1.2: Outline the stages of signal transduction.
C2.1.3: Explain the mechanism of quorum sensing in bacteria and discuss its role in bacterial behaviour.
C2.1.4: Understand bioluminescence and its importance and applications.
C2.1.5: Identify the categories of signalling chemicals in animals ­ hormones, neurotransmitters, cytokines and calcium ions.
C2.1.6: Differentiate between different types of signals used by multicellular organisms.
C2.1.7: Describe the difference in structure and function of hormones and neurotransmitters.
C2.1.8: Demonstrate an understanding of mechanisms that signalling molecules use to produce localised as well as distant effects.
C2.1.9: Analyse the role of signalling molecules in the transmission of signals from one part of the body to another.
C2.1.10: Compare and contrast transmembrane receptors and intracellular receptors.
C2.1.11: Describe the different signalling pathways activated by transmembrane receptors and intracellular receptors.
C2.1.12: Explain the mechanisms of initiation of signal transduction pathways.
C2.1.13: Compare and contrast different types of transmembrane receptors and their mechanisms of action, including neurotransmitter receptors and G protein-coupled receptors.
C2.1.14:Analyse the role of transmembrane receptors in changing membrane potential and activating intracellular signalling pathways.
C2.1.15: Explain that positive feedback amplifies the response.
C2.1.16: Explain that negative feedback dampens or inhibits the signalling response.
C2.1.17: Explain that a balance of both positive and negative feedback is necessary for proper cellular response