Which of the following, A to D, is not an example of cell signalling?
The passive diffusion of oxygen from the alveoli into blood capillaries.
The neurotransmitter glutamate binding to receptors on a post-synaptic neuron.
The hormone adrenaline binding to receptors on cardiac muscle cells.
Macrophages releasing interleukins to activate T-lymphocytes.
19 exam-style questions on OCR A A Level Biology Communication and homeostasis. Each one has a worked solution and a mark scheme showing where the marks go.