Plants chapter 29 AP Biology: overview

Key Concepts: zThe plant kingdom consists mostly of multicelled photoautotrophs zAlmost all plants live on land zPlants have structural adaptations that allow them to photosynthesize, absorb water and ions, and conserve water zLand plants are reproductively adapted to withstand dry periods

Key Concepts: zSeed producers were more successful in radiating into drier environments based on an evolutionary scale zGymnosperms and angiosperms are vascular plants zAngiosperms include two classes of flowering plants yDicots and Monocots

Evolutionary Trends Among Plants zPhotoautotrophs zVascular plants yRoots, stems, leaves yGymnosperms xSeed bearing xGingko xCycads xConifers z Angiosperms yFlowers and seeds yDicots and Monocots z Non-vascular plants yBryophytes xLiverworts xHornworts xMosses

Evolution of Roots, Stems, and Leaves zRoots and Stems yBelow ground zShoot systems yStems and leaves yAbove Ground xSunlight and CO 2 ySupport of cell wall xLignin z Vascular tissue yXylem yPhloem z Water conservation yCuticle yStomata

Evolutionary Trend Among Plants Alternation of generations

Evolution of Pollen and Seeds zHomospory zHeterospory yPollen grains xSperm-bearing gametophytes xFemale gametophytes ySpread by air, insects, birds zSeeds yEmbryo of gametophytes yNutritive tissues yProtective coat

Bryophytes zMosses zLiverworts zHornworts yNonvascular yMoist habitats mostly ySmall x< 20 cm tall ySimplest plants

Bryophytes

Moss Life Cycle

Existing Seedless Vascular Plants zWhisk ferns, Lycophytes, Horsetails, Ferns y3 Differences from Bryophytes xSporophyte not attached to a gametophyte xHas vascular tissues xLonger phase in life cycle yHabitat xMoist places yGametophytes lack vascular tissue xSperm needs water to reach egg

Life Cycle of a Fern

The Rise of the Seed-Bearing Plants zSeed ferns, gymnosperms, angiosperms yPollen grains xMale gametophytes yOvules xEgg producing gametophytes yPollination xPollen grains arrive on female reproductive structures xIndependent of water for fertilization

Note the decrease in size of Gametophyte generation

Important Adaptations for land plants Vascular tissue transports water and nutrients to the body of the plant Cuticle provides an effective barrier to water loss Stomata bordered by guard cells that regulate opening, and thus water loss

Ferns

Spore of A Lycophyte

Seed-Bearing Plants zDepend on yPollen grains yOvules that mature into seeds yTissue changes adapted to dry conditions

Gymnosperms- Plants with “Naked” Seeds zConifers, Cycads, Ginkgos, Gnetophytes yConifers - cones xPines, cypress, firs, spruces, redwoods

Lesser Known Gymnosperms zCycads yTropical Subtropical areas yLargest seed- bearing cones yZamia in Florida zGingko yGingko biloba yDiverse in dinosaur times z Gnetophytes yGneton xTropics yEphedra xCalifornia yWelwitschia mirabilis xDeserts in Africa

Pines

Angiosperms The Flowering Seed-Bearing Plants zFlowers zCoevolution with pollinators yInsects Bats Birds ySeed yOvary

Dicots and Monocots zAlmost 180,000 Dicots are herbaceous yCabbage and Daisies yFlowering shrubs and trees yWater lilies yCacti zAbout 80,000 Monocots yOrchids, palms, grasses, crop plants, rice

In Conclusion zPlants probably arose from green algae zTrends in evolution can be identified by comparing structural adaptations to dry conditions, shifts to diploid dominance, and the shift to heterospory zBryophytes are nonvascular plants and require free water for fertilization zVascular plants are adapted to life on land

In Conclusion zGymnosperms are vascular plants that produce pollen grains and seeds zOvules contain the egg-producing female gametophytes zEvolution of pollen grains freed these plants from dependence on water for fertilization zAngiosperms produce flowers and coevolved with pollinators