AP Review Chapters 29-31, Fast Facts There are four main groups of land plants: bryophytes, pteridophytes, gymnosperms, and angiosperms Bryophytes: mosses; distinguished from algae by advances that allow for life on land Pteridophytes: ferns; contain vascular tissue (transport water and food); “seedless plants” Fast Facts Gymnosperms:conifers; “naked seed” (seeds are not enclosed in a special chamber) Seed: consists of a plant embryo packaged with food and a protective coat Angiosperms: flowering plants; “container seed”; most modern-day plants algal ancestors bryophytes vascular plants the origin of seeds the evolution of flowers Fast Facts Charophyceans are the green algae most closely related to land plants Several terrestrial adaptations distinguish land plants from charophycean algae - growth in length is from apical meristems - multicellular, dependent embryos - alteration of generations: gametophyte and sporophyte Fast Facts Fast Facts Fast Facts Adaptations for water conservation: - formation of a cuticle - stomata contain guard cells Adaptations for water transport: - xylem: carry water and minerals up from root - phloem: distribute sugars and amino acids throughout the plant Fast Facts The gametophyte is the dominant generation in the life cycle of bryophytes Modern vascular plants include ferns (pteridophytes), gymnosperms, and flowering plants (angiosperms) Differ from bryophytes - contain phloem and xylem - dominant sporophyte generation Fast Facts Fast Facts Seed plants are vascular plants that produce seeds The developing embryo is encased in a protective seed coat and supplied with its own source of food (endosperm or cotyledons) Fast Facts Fast Facts Seeds allow the embryo to be moved away from the parent by wind, water, and animals Seed plants are not tied to water for fertilization; pollen grains do not need to be transported by liquid Fast Facts Gymnosperms lack enclosed chambers in which seeds develop; instead, seeds develop on the surfaces of specialized leaves called sporophylls. Phylum Anthophyta: - all angiosperms are placed in one phylum Two classes: monocots and dicots Fast Facts - have vessel elements for water transport instead of tracheids; speed water transport through the plant Fast Facts Fast Facts All fungi are eukaryotic; most are multicellular mycete = fungi Fungi differ from plants in nutritional mode, structural organization, growth, and reproduction Fungi are heterotrophs that acquire their nutrients by absorption Fast Facts The bodies of fungi are constructed of tiny filaments called hyphae - the hyphae are divided into cells by cross-walls, or septa - cells walls are made of chitin Fast Facts Lichens - symbiotic relationship of millions of photosynthetic microorganisms held in a mesh of fungal hyphae - the alga provides the fungus with food. The fungus provides a suitable environment for growth Fast Facts Fast Facts Mycorrhizae - mutualistic association of plant roots and fungi - responsible for making nutrients able to be absorbed Sample Questions Discuss the adaptations that have enabled flowering plants to overcome the following problems associated with life on land. a) The absence of an aquatic environment for reproduction. b) The absence of an aquatic environment to support the plant body c) Dehydration of the plant Fast Facts Plants are made up of two main systems: the root system and shoot system Monocots have fibrous roots: mat of thin roots that spread out below the soil surface Dicots have a taproot: one large vertical root that produces lateral branch roots Fast Facts Stem - an alternating system of nodes (place where leaves are attached) and internodes (the stem between the nodes) - apical dominance: growth focuses on the terminal bud; inhibits the axillary bud Fast Facts Leaves - main photosynthetic organ of plants - consist of a flattened blade and a petiole (stalk that join to the node of the stem) - monocots have parallel veins in leaves - dicot leaves have a multi-branched network of veins Fast Facts Plant organs are composed of three tissue systems: dermal, vascular, and ground Dermal tissue - single layer of tightly packed cells that covers and protects all young parts of the plants - for the cuticle Fast Facts Vascular tissue - involved in the transport of materials between the root and the shoot - xylem: moves water and dissolved minerals upward from roots - tracheids and vessel elements are elongated cells that are dead at functional maturity Fast Facts Fast Facts - phloem: moves food made by leaves to the roots - sieve-tube members transport sucrose and other organic materials - sieve plates help move fluid from cell to cell - companion cell: assist the STM Fast Facts Ground tissue - tissue that is neither dermal nor vascular - in dicots, divided into the pith (internal to the vascular tissue) and the cortex (external to vascular tissue) - photosynthesis, storage, and support Fast Facts Plant tissues are composed of three basic cell types: parenchyma, collenchyma, and sclerenchyma Parenchyma cells - have 1o cell walls, but lack 2o - typical plant cell; least specialized - perform most metabolic functions of the plant Fast Facts Collenchyma cells - thicker 1o cell walls - support young parts of the plant shoot - provide support without restraining growth Sclerenchyma cells - support; form thick 2o cells that are strengthened by lignin - dead at functional maturity - ex. xylem cells Fast Facts Vascular tissue runs through the stem in strands called vascular bundles - surrounded by ground tissue In dicots, the vascular bundles are arranged in a ring, with the pith inside the ring, the cortex is outside In monocots, the vascular bundles are scattered throughout the ground tissue Fast Facts Fast Facts Tissue organization of leaves The epidermis is composed of tightly interlocked cells - stomata: tiny pores that allow for gas exchange w/ the help of guard cells The ground tissue is sandwiched between the upper and lower epidermis in the mesophyll Fast Facts - the mesophyll consists of parenchyma cells w/ chloroplasts The vascular tissue also flows through the leaf from the stem - contains the xylem and phloem Fast Facts Differences in water potential drive water transport in plant cells Osmosis: the net uptake or loss of water by a cell Water potential: the combined effect of solute concentration and pressure. - psi (Y) - water will move from the solution with the higher water potential to the solution with the lower water potential Fast Facts Bulk flow: the movement of fluid driven by pressure Root pressure: water flows in from the root cortex, generating a positive pressure that forces fluid up the xylem Root pressure causes guttation: when more water enters leaves than is transpired and the excess is forced out Fast Facts Pulling up xylem sap: TranspirationCohesion-Tension Theory Transpiration -when stomata open water exits the leaf - move from [high] to [low] Cohesion - water molecules will bond to each other with hydrogen bonds Fast Facts Hormones: chemical signals that coordinate the parts of an organism Tropism: any growth response that results in curvatures of whole plant organs toward or away from stimuli Phototropism: the growth of a shoot toward light Fast Facts Auxin (IAA) - any chemical substance that promotes the elongation of coleoptiles - moves from the shoot tip down to the base of the plant Cytokinins - stimulate cytokinesis, or cell division Fast Facts Gibberellins - stimulate growth in the stems and leaves, but not in the roots - stimulates cell elongation and division Abscisic Acid - slows down growth - seed dormancy: high levels of ABA inhibit germination; only when the ABA is inactivated will the seed germinate Fast Facts Ethylene - produced by plants in response to environmental stresses - also occurs in fruit ripening and programmed cell death Sample Questions Angiosperms (flowering plants) and vertebrates obtain nutrients from their environment in different ways: (A) Discuss the type of nutrition and the nutritional requirements of angiosperms. (B) Describe 2 structural adaptations in angiosperms for obtaining nutrients from the environment. Relate structure to function. (C) Interdependence in nature is evident in symbiosis. Explain two symbiotic relationships that aid in nutrient uptake, using examples from angiosperms.