= Solution
\b[The new bud contains newly deposited wall rather than simply inheriting a stretched patch of the mother's old labelled wall.] <concanavalin A> conjugated to <FITC> was applied before growth resumed, so it marks the pre-existing accessible <biological cell> surface. The bright mother outline persists while the emerging bud is weakly labelled or unlabelled. That spatial contrast places substantial new, unlabelled wall material at the growth site. Drug-treated <biological cells> that eventually bud show that at least some localized new wall deposition still occurs under treatment.
The pulse label does not mark all wall made subsequently, and it does not prove that absolutely no new material is inserted elsewhere in the mother. Signal dilution, shedding and accessibility can affect brightness. A second distinguishable wall label applied after refeeding would more directly map new deposition. If the original <lectin> remained free in the medium, it would also bind newly exposed wall, so the interpretation assumes the stated prelabelling step functions as a pulse rather than continuous staining.
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