Exam 4 Study GuideEarly Development of the Plant Body• What is an embryo? Are seed plants the only plants to produce embryos?o An embryo is a young sporophyte before the start of a period of rapid growth (germination in seed plants). o Seed plants are not the only plants to produce embryos (i.e. seedless vascular plant Selaginella).• How is polarity important in the embryonic development of plants? Embryogenesis, apical-basal pattern, radial pattern, polarity, embryo proper, suspensor, axis, micropylar pole, chalazal pole.o Establishment of polarity is important to the embryonic development of plants because it fixes the structural axis of the body upon which lateral appendages will be arranged.o Embryogenesis: Development of an embryo from a fertilized egg, or zygote.o Apical Basal Pattern: pattern of tissue organization that is vertical (i.e. root vertically to shoot).o Radial Pattern: pattern of tissue organization that is outward growth (i.e. the cross section of the stem). o Polarity: how the plant axis is set up.o Embryo proper: will give rise to the tissue systems of the plants.o Suspensor: a structure at the base of the embryo in many vascular plants. o Axis: line of the body of the plant in which the lateral appendages will be arranged.o Micropylar pole: Part of the axis that will turn into the micropyle in the mature gametophyte.o Chalazal pole: part of the axis that will turn into the chalaza in the mature gametophyte.• What are the three primary meristems of plants, and which tissues do they form. Protoderm, ground meristem, procambium, apical meristem, primary meristems, periclinal division, epidermis, ground tissue, vascular tissue.o The three primary meristems of plants are: Protoderm: Forms the epidermis (dermal tissue system). Ground Meristem: Forms the ground tissues (parenchyma, collenchyma, and sclerenchyma) (ground tissue system). Procambium: Forms the Primary xylem and primary phloem (vascular tissue system).o Apical Meristem: The meristem at the tip of the root or shoot in a vascular plant.o Primary meristems: tissue derived from the apical meristem; of three kinds: protoderm, procambium, and ground meristem. o Periclinal Division: when cell division occurs parallel to the length of the existing cell.o Epidermis: the outermost layer of cells of the leaf and young stems and roots; primary in origin.o Ground tissue: Tissue other than the vascular tissues, the epidermis, and the periderm. Also called fundamental tissue. o Vascular tissue: Conducting tissue of water and nutrients (xylem and phloem).• What structures nourish the developing embryo? What structures nourish the seedling prior to establishment? Suspensor, endosperm, perisperm, cotyledons, hilum, funiculus.o Food reserves flow through the funiculus of the ovule. Sources of nourishment to the developing embryo also come from the suspensor, endosperm, perisperm, and cotyledons.o Suspensor: is metabolically active and supports early development of the embryo proper, providing nutrients and growth regulators.o Endosperm: Is triploid and is unique to angiosperms. Nourishes the young sporophyte before and/or after germination of the seed.o Perisperm: food storing tissue derived from the nucellus that occurs in the seeds of some flowering plants.o Cotyledons: Seed leaf; generally absorbs food in monocots and stores food in other angiosperms.o Hilum: Scar left on a seed after its separation from the funiculus.o Funiculus: The stalk of the ovule where food reserves flow into the ovule.• What are the main parts of a mature eudicot embryo? A mature monocot embryo? Hypocotyl, epicotyl, plumule, radicle, hypocotyl-root axis, scutellum, coleorhiza, coleoptile.o The main parts of a mature eudicot embryo are the hypocotyl, epicotyl, radicle, and plumule.o The main parts of a mature monocot embryo are the scutellum, coleorhiza, and the coleoptile.o Hypocotyl: the portion of an embryo or seedling situated between the point of attachment of the cotyledons and the radicle. o Epicotyl: The upper portion of the axis of an embryo or seedling, above the point of insertion of the cotyledons and below the next leaf or leaves.o Plumule: the embryonic shoot, which may consist of an epicotyl, one or more young leaves, and an apical meristem. It is above the cotyledons.o Radicle: The embryonic root.o Hypocotyl-root Axis: The embryo axis below the point of attachment of the cotyledon or cotyledons, consisting of the hypocotyl and the apical meristem of the root or radicle. Used when the radicle cannot be distinguished in an embryo.o Scutellum: The single cotyledon of a grass embryo, specialized for absorption of the endosperm.o Coleorhiza: The sheath enclosing the radicle in the grass embryo.o Coleoptile: The sheath enclosing the apical meristem and leaf primordial of the grass embryo; often interpreted as the first leaf.• What factors affect the timing of seed germination? Germination, dormancy, after-ripening.o Some factors that affect the timing of seed germination are the maturity of the embryo, amount of water, amount of oxygen, temperature, and light. o Germination: the beginning or resumption of growth by a spore, seed, bud, or other structure.o Dormancy: a special condition of arrested growth in which the seeds do not begin to grow without special environmental cues. The special environmental cues prevent the breakdown of dormancy during superficially favorable growing conditions.o After ripening: metabolic changes that must occur in some dormant seeds before germination can occur (typically triggered by environmental cues).• How do the steps following germination (prior to seedling establishment) differ among plants? What structure typically emerges first from the seed? What alternative strategies are used by plants to protect their apical meristems? Primary root, tap root, lateral roots, shoot-borne roots, hook, epigeous germination, hypogeous germination.o The first structure that typically emerges first from the seed is the root (absorbs water and anchors seedling). o The steps following germination differ among plants in that they can either undergo epigeous germination or hypogeous germination.o Primary Root: The first root of the plant, developing as a continuation of the root tip or radicle of the embryo; the taproot. o Taproot: The
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