Grazing by the mule deer releases signals which activate or prompt production of defense compounds, as well as eliminating shoot tips which had been inhibiting outgrowth of axillary buds via auxin signalling, among other mechanisms. Then, the axillary buds can grow out as new branches to help replace what the mule deer has eaten. There may be a temporary decline in plant health since photosynthetic tissue has been removed, but the new branches can more than make up for this loss.
Work Step by Step
Review the chapter and make a list of all phenomena related to herbivory and to shoot tips. Then use this list of facts, matched to the grazing of the mule deer, to construct a list of what the plant will do/change as it responds.