Practice question

Asymmetric division of zygote produces small apical cell forming embryo proper and large basal cell dividing transversely generating file of suspensor cells connecting embryo to maternal tissue and endosperm. Thus embryonic suspensor derives entirely from basal lineage specified by high WOX8/WOX9 expression, auxin efflux toward basal pole, and activated downstream transcriptomes. Suspensor facilitates nutrient transport, hormone supply, and mechanical positioning of embryo within seed cavity. Its uppermost cell hypophysis contributes quiescent center and columella stem cells. Basal origin demonstrates early lineage separation between embryonic and extraembryonic supportive tissues.