Practice question

Unicellular to multicellular transition is triggered by nutritional status rather than oxygen, pH, or temperature cues dominant in soil microenvironment. Decline in bacterial prey reduces intracellular amino acids and folate, decreasing TORC1 activity, activating YakA protein kinase, and permitting expression of early developmental proteins. Folate receptor downregulation and cAR1 upregulation switch chemotaxis preference from bacteria to cAMP. Nutrient depletion also induces autophagy providing metabolites for development without external food. Oxygen depletion would affect aeration but not initiate aggregation, pH increase and temperature drop are unreliable signals, making nutrient limitation authentic ecological trigger inducing survival morphogenesis and fruiting.