Practice question

Cotyledons represent first embryonic leaves formed during heart stage when auxin maxima at apical margins trigger localized outgrowth from globular mass converting to bilateral symmetry. During this transition globular embryo converts to triangular heart morphology with two bulging primordia containing emerging provascular strands and accumulating storage products. Cotyledon formation involves coordinated action of PIN1-dependent auxin transport creating convergence maxima, CUC boundary genes establishing separation, and LEC regulators promoting maturation. Their emergence during heart stage establishes photosynthetic and nutritional support organs essential for seedling survival and reflects successful bilateral patterning and lateral organogenesis program.