Final answer:
Waves of cAMP cause Dictyostelium cells to respond at the cellular level by activating protein kinase A (PKA) and initiating a signaling cascade.
Step-by-step explanation:
The waves of cyclic AMP (cAMP) cause Dictyostelium cells to respond at the cellular level. When cAMP binds to its receptors, it activates protein kinase A (PKA), initiating a signaling cascade that leads to various cellular responses. For example, in liver cells, the fight-or-flight response to adrenaline is mediated by cAMP, which activates PKA and triggers a cellular response.