Practice question

The Dictyostelium slug displays pronounced positive phototaxis and thermotaxis, moving toward light and warmer areas of soil surface. Anterior prestalk tip functions as organizer sensing light via putative rhodopsin-like mechanism and lens effect, translating photic cues into altered cAMP and ammonia signaling. Light reduces ammonia retention at tip, loosening slug and steering migration. Orientation toward bright areas positions future fruiting body for efficient wind dispersal of spores away from depleted bacterial zones. Movement toward dark, moist, or dry microenvironments would retain spores underground, reducing fitness, making phototaxis essential for successful dispersal and life cycle completion.